Nitrogen ligands: The transition metal catalyzed reaction of ... - NOPR [PDF]

Indian Journal of Chemistry Vol. 44B, September 2005, pp. 1894-1908

Nitrogen ligands: The transition metal catalyzed reaction of aryl halides with olefins (Mizoroki-Heck), phenylboronic acid (Suzuki coupling) and BuchwaldHartwig amination, new catalysts and effect of co-catalysts ⎯ Aryl halide activation ⎯ Part I Suresh Iyer*, Girish M Kulkarni, C Ramesh & Aruna K Sattar Organic Chemistry Synthesis Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India E-mail: [email protected] Received 5 April 2004; accepted (revised) 24 March 2005 Nitrogen ligands are an excellent alternative for the traditional P-ligands in the Pd catalyzed Mizoroki-Heck reaction, Suzuki coupling and Buchwald-Hartwig aryl amination. Pd complexes of dimethyl glyoxime, 8-hydroxyquinoline, salen, picolinic acid, and DAB ligands gave high yields of the E-cinnamates and E-stilbenes from aryl iodides. Acetophenone oxime N, N-dimethybenzylamine and ferrocenyl oxime palladacycle are better catalysts with comparable yields, high TON (95, 000) and TOF′s (2, 500 h-1) to P-ligand catalysts. Aryl bromides and in a few cases, aryl chlorides could also be activated by these complexes by the use of Lewis acid and (C4H9)4NI as additives. Cy-DAB ligands gave good yields with electron rich aryl bromides and the use of ionic liquid improve the yield. These N-ligand metal complexes can be readily synthesized and the ligands possess the advantage of easy functional group modifications and convenient synthetic methods compared to P-ligands. The degradation reactions associated with P-ligands are not observed in the N-ligands, with comparable, high thermal, moisture and air stability and insensitivity. Activation of aryl bromides (Mizoroki-Heck reaction, Suzuki reaction) could be achieved in high yields, TON and TOF (86-94% yield, TON: 36, 000-90, 000, TOF: 6, 000-11, 500 h-1) catalyzed by monomeric amine and oxime palladacycles (Cat-8, 11, 13 B) with a N-heterocyclic carbene ligand better than a phosphorous ligand. Molten (C4H9)4NBr is an efficient ionic liquid medium for the Mizoroki-Heck reaction of aryl bromides, giving higher yields. Low to moderate yields of aryl amination are obtained with the carbene palladacycle and N, N-dibenzyl piperazine Pd complexes.

Keywords: Nitrogen ligands, Mizoroki-Heck reaction, DMG, DAB, palladacycle IPC: Int.Cl.7 C 07 C, C 07 D

The Pd catalyzed reaction of aryl and vinyl halides with olefins (Mizoroki-Heck reaction), phenyl boronic acid (Suzuki coupling) and BuchwaldHartwig aryl aminations are well studied reactions and generally use phosphine and phosphites as ligands1. Cyclopalladated tris-o-tolylphosphine, N-heterocyclic carbene, tridentate aryl bisphosphine Pd (II) (PCP), triaryl phosphites, are excellent catalysts giving high yields, TON and TOF2. A major drawback of the use of phosphine ligands in such catalytic reactions is the oxidation of the phosphine to a phosphine oxide as well as cleavage of the P-C bond, causing degradation of the ligand, reduction of the metal and termination of the catalytic cycle3. Cyclopalladated aromatic rings are the chosen catalyst ⎯⎯⎯⎯⎯⎯ NCL Communication No.: 6665

systems due to the high thermal, moisture and oxidative stability. Nitrogen compounds are a commonly used ligands in transition metal chemistry and equal in number and reactions to P-ligands4. A variety of novel C-N, C-S palladacycles incorporating NHC5, imine6, thioether7 and oxime8 have been reported with high turnover numbers up to 105-106. These palladacycles are thermally stable and insensitive to moisture and air. Phosphine ligands have also been successfully used in the Ni, Cu, Co, Ir, Rh, Pt catalyzed reactions of aryl and vinyl halides with olefins, aryl boronic acids and amines9. Nitrogen ligands like DMG, 8-hydroxyquinoline, salen, picolinic acid, tmeda and their metal complexes and palladacycles from substituted N,N-dimethylbenzylamine, benzaldoxime and benzophenone oxime can be easily synthesized from readily available precursors by a variety of convenient synthetic

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

methods10. Such ligands are not as readily oxidizable as phosphines and the metal complexes with a covalently bonded Pd to the aromatic ring, could be more stable and efficient catalysts (Scheme I) and activate unreactive bromides and chlorides11. These various ligands also offer scope for electronic tuning by easy functionalization to influence the reaction in the desired direction including asymmetric induction (Schemes II-IV)12. The Pd catalyzed Suzuki reaction of phenyl boronic acids with aryl halides is an important methodology for the synthesis of unsymmetrical biaryls. Several Pd, Ni homogeneous catalysts,

1895

heterogeneous catalysts on polymer, zeolites, clay, nano particle, have been reported for this reaction13. Ni and Cu salts catalyze the amination of aryl halides at high temperatures14. The nucleophilic substitution of aryl halides is catalyzed by Cu salts15. The Buchwald-Hartwig Pd catalyzed amination of aryl halides in the presence of strong bases proceeds in high yields under moderate reaction conditions16. Results and Discussion Reaction of DMG, DAB, 8-hydroxyquinoline, salen and picolinic acid with PdCl2 by well established procedures gives the corresponding Pd (II)

N

+

Δ

PdCl2

N

C2H5OH

N

Pd

O

O

OH

Cat 1 - Pd (Oxine)2

N

CH 3

Cl Pd

OH N

O

O

Cl

O

N

Cl

O

Pd CH 3

N OH

Cl

N

Pd

N

Cat 3 - Pd (Pic)2

Cat 2 - Pd (DMG)Cl2

Cat 4 - Pd (Cy-DAB)Cl2

OCH3

N

Cl

N Pd N

Cl Pd

Cl

N

Cl

OCH 3

Cat 6 - Pd (2, 6-iPr-DAB)Cl2

Cat 5 - Pd (4-Anis-DAB)Cl2

Scheme I ⎯ Preparation of dimethylglyoxime, 8-hydroxyquinoline, di-imine palladium complexes

N(CH3)2

R

PdCl2, LiCl

R

N(CH 3)2

CH3OH

N-OH

Pd Cl

PdCl2, LiCl

N-OH

CH3OH

Pd

2

Cat 8 - Amine Pd dimer

R : H : Cat 9 C6H5 : Cat 10 CH3 : Cat 10 A

Scheme II ⎯ Preparation of amine and oxime palladacycles

Cl

2

INDIAN J. CHEM., SEC B, SEPTEMBER 2005

1896

CH 3

CH3 N-OH

N-OH

+

Fe

Pd

LiCl

PdCl2

Fe Cl 2

CH3OH

Cat 11 - Ferrocenyloxime Pd CH3

CH 3

N-OH

N-OH Pd

Pd

Fe Cl 2

Fe Cl

PR3 : P(C6H5)3 P(OC2H5)3

Cat 11 - Ferrocenyloxime Pd dimer

PR3

Cat 12 A, B - Ferrocenyloxime Pd Cycle

Scheme III ⎯ Preparation of ferrocenyl oxime palladacycle R

R N(CH3)2 Pd Cl

Cat 8

2

N-OH

or

Pd Cl

2

Δ, Toluene C6H 5

C6H5

N

N

N

Cat 10, 10A R : C6H5, CH3

N

C6H 5 C6H 5

N(CH 3)2 C6H 5

Pd N

Cl

N-OH

Cat 13 C

N

Cl

N C6H 5

C6H 5

Pd

,

N C6H 5

Cat 13 A, B - NHC Pdcycle R = CH3, C6H5

Scheme IV ⎯ Preparation of saturated N-heterocyclic carbene palladacycles

complexes in high yield17. In all these complexes, the metal is in the 2+ oxidation state. The DAB ligands are readily prepared by the condensation of various amines and 1,2-diammines with glyoxal and 2,3butanedione (compared with the tedious synthesis of phosphines). The strong σ-donor and π-acceptor properties of the DAB make them excellent ligand for the activation of the less reactive aryl bromides and chlorides. Salen and picolinic acid with the-COOH and-OH bonding to Pd, offer different electronic properties to these catalysts. Cyclopalladation of benzaldehyde oxime, acetophenone oxime, benzophenone oxime, N,N-dimethylbenzylamine and acetylferrocenyl oxime is facile and

carried out according to the reported literature procedure to give the dimeric palladacycles5e,f. Ferrocene is an electron rich aromatic metal complex and has interesting properties due to its sandwich nature. The electron rich ferrocene was also expected to increase the electron density on the Pd enabling activation of less reactive aryl halides. Monomeric complexes of the dimeric palladacycles (12 A, B, 13 A, B, C) (Table I) were prepared for studying the ligand effect by complexation to P(C6H5)3, P(OC2H5)3 and saturated N-heterocyclic carbenes18. N-heterocyclic carbene orthopalladated oxime and amine catalysts (13 A, B, C) were prepared by the refluxing of the corresponding dimeric palladacycles with the

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

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Table I ⎯ Nitrogen ligand-Pd catalyzed Mizoroki-Heck reaction S. No.

Aryl bromide

Olefin

Catalyst

Time (hr)

Yield (%)

24 8 24 24 8 24 24 24 24 24 24 24 48

69 68 84 48 48 57 NR 16 8 64 46 64 15

1.

4-Cl.C6H4.I (14)

C5H8O2a

2.

C6H4.Br (15)

C5H8O2

3.

4-HO.C6H4.Br (16)

C8H8

4. 5. 6.

4-HO.C6H4.Br 4-(CH3)2N.C6H4.Br (17) C6H5Br (18) (50 mmoles)

C8H8 C5H8O2 C8H8h (50 mmoles)

1– Pd(C9H6NO)2 2-Pd(DMG)Cl2 3–Pd(2-COOH.C5H4N)2 1– Pd(C9H6NO)2 2-Pd(DMG)Cl2 3–Pd(2-COOH.C5H4N)2 1– Pd(C9H6NO)2 2-Pd(DMG)Cl2 3–Pd(2-COOH.C5H4N)2 4 4 4 4A

7.

1-C10H7Br (10 mmoles) (19)

C8H8

4

3

86

8.

1-C10H7Br (10 mmoles)

C8H8

4A

6

76

9.

4-CH3O.C6H4.I (20) (50 mmoles)

C5H8O2 (100 mmoles)

8 (0.0005)

8

88

(25 mmoles)

(50 mmoles)

11 (0.00026)

12

65

(25 mmoles)

(50 mmoles)

12A (0.00155)

12

84

(25 mmoles)

(50 mmoles)

12B (0.00026)

12

92

C6H5.Br (50 mmoles)

C5H8O2 (100 mmoles)

8 (0.0005)

34

90

(50 mmoles)

(100 mmoles)

9 (0.0005)

48

52

C6H5.Br (18) (50 mmoles)

C8H8 (60 mmoles)

8 (0.0005)

29

86.6

(50 mmoles)

(60 mmoles)

10 (0.0005)

1

96

1-C10H7.Br (21) (25 mmoles)

C5H8O2 (50 mmoles)

13 B (0.00036)

7

93.2

(25 mmoles)

(50 mmoles)

13 C (0.0004)

9

86.3

1-C10H7.Br (10 mmoles)

C8H8 (10 mmoles)

11 (0.00026)

2

94

(25 mmoles)

(30 mmoles)

13 C (0.0004)

7

86.8

10.

11.

12.

13.

TON (TOF)

64 46 64 37, 600 (783) c 17, 200 (5,733)d 380 (63)e 89,540 (11, 190) 62, 500 (5, 208) 14, 000 (1, 166) 88, 461 (7, 371) 90, 000 (2, 647) 72, 000 (240) 90, 000 (2, 647) 483 (483) 65, 019 (9, 288) 53, 925 (5, 991) 36, 538 (11, 529) 59, 500 (8, 500) ⎯ Contd

INDIAN J. CHEM., SEC B, SEPTEMBER 2005

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Table I ⎯ Nitrogen ligand-Pd catalyzed Mizoroki-Heck reaction ⎯ Contd S. No. 14.

15.

16.

17.

18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28.

Aryl bromide 4-4-CH3O.C6H4.Br (22) (10 mmoles)

Olefin C8H8 (20 mmoles)

4-NO2.C6H4.Cl (23) (50 mmoles)

C8H8 (60 mmoles)

4-COCH3.C6H4.Cl (24) (10 mmoles)

C8H8 (16 mmoles)

4-CN.C6H4.Cl (25) (5 mmoles) (10 mmoles)

C8H8 (6 mmoles) (16 mmoles)

2-Br.C5H4.N (26) (5 mmoles) 4-CH3O.C6H4.I 4-CH3O.C6H4.I 4-CH3O.C6H4.I 4-CH3O.C6H4.I 4-CH3O.C6H4.I 4-NO2.C6H4.I (27) 2-Cl.C5H4N 2-Cl.C5H4N 4-CH3O.C6H4.I 4-CH3O.C6H4.I

C5H8O2 (10 mmoles) C8H8 C8H8 C5H8O2 C5H8O2 C5H8O2 C5H8O2 C5H8O2 C5H8O2 C5H8O2 C5H8O2

Catalyst

Time (hr)

Yield (%)

TON (TOF)

13 A (0.0016)

10

86.5

13 B (0.0014)

7

67.8

13 C (0.0018)

24

50

5, 461 (546) 923 (703) 2, 777 (116)

8 (0.0005) 9 (0.0005)

42 40

71 69

70, 000 (9) 350 (8)

13 A (0.0018) 13 B (0.0023) 13 C (0.001)

24 24 24

54.9 75.7 61.4

3, 103 (129) 3, 347 (139) 3, 070 (128)

8 (0.0005) 13 A (0.0018) 13 B (0.0017) 13 C (0.002)

20 24 24 24

78.5 73.4 70 34

350 (14) 4, 111 (171) 3, 902 (162) 1, 705 (71)

9 (0.0005) 17A-Ni(C16H14N2O2) 17B-Mn(C16H14N2O2) 17C-Cu(C16H14N2O2) MnO2 PdCl2{P(C6H5)3}2 PdCl2{P(C6H5)3}2 9-{PdC13H10ClNO}2 Pd(OCOCH3)2 Ni/Al2O3 {IrCl(COD)}2/Cy-DAB

48 24 24 24 24 12 18 24 4 2 32

68 42 21 60 80 90 40 60 50 95 75

4, 090 (85)

a: C5H8O2-Ethyl acrylate; b: C8H8-Styrene c: Halide: Olefin: Base: Cat-4A: Cy-DAB: 50:50:55:0.0002: 0.0004-Temp: 140°C; d: Halide: Olefin: Base: Cat-4A: Cy-DAB: 10:10:15:0.02: 0.04-Temp: 140°C: e: Halide: Olefin: Base: Cat-4A: Cy-DAB: 10:10:15:0.02: 0.04-Temp: 120°C; NR: No Reaction

saturated N-heterocyclic carbene dimers in m-xylene in moderate yield. The ferrocene ring and the Nheterocyclic carbenes impart greater air, moisture and thermal stability to the palladacycles (12 A, B, 13 A, B, C) as well as increase its activity5. The Pd (II) (Cat-1, 2, 3) catalyzed reaction of 4chloroiodobenzene 14, bromobenzene 15 and 4bromophenol 16 with styrene and ethyl acrylate gave moderate to high yields of the E-cinnamates (14, 15) and E-stilbenes 16 (Table I). Higher yields for the reaction of 4-bromophenol and 4-N,N-dimethylamino bromobenzene with styrene 17A and ethyl acrylate 17 were obtained with the Pd-DAB catalysts (Cat-4). 1Bromonaphthalene reacted with styrene for 3 hr to

give 86% yield of the E-naphthylstilbene (19, TON17, 200, TOF-5, 733)21. The same reactions of bromobenzene (50 mmoles) with styrene (50 mmoles) in the presence of Pd (0) (Cat-4A-Pd(dba)2/Cy-DAB) gave only 15% yield in 48 hr(18, TON-37, 600, TOF783), while the reaction of 1-bromonaphthalene (10 mmoles) with styrene gave 76% yield of E-stilbene (TON-380, TOF-63). 4-Iodoanisole (50 mmoles), bromobenzene (50 mmoles) and 1-bromonaphthalene (25 mmoles) reacted with ethyl acrylate and styrene in the presence of catalysts (8, 9, 11, 12A, 12B, 13B, 13C) to give the corresponding E-4-methoxyethyl cinnamate (20, Cat8, 88%, TON-89, 540, TOF-11, 190), E-ethyl

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

cinnamate (22, Cat-8, 90%, 90, 000, TOF-2, 647), Estilbene (Cat-10, 96%, TON-483, TOF-483), E-1naphthyl cinnamate (21, Cat-13 B, 93.2%, TON-65, 019, TOF-9, 288) and E-1-naphthyl stilbene (19, Cat11, 94%, TON-36, 538, TOF-11, 529)21. Electron deficient aryl chlorides, 4-nitrochlorobenzene (50 mmoles), 4-chloroacetophenone (10 mmoles), 4-chlorobenzonitrile (10 mmoles) also reacted with styrene to give high yields of (E)-4nitrostilbene (23, Cat-8, 71%, TON-70, 000, TOF-9), (E)-4-acetylstilbene (24, Cat-13 B, 75.7%, TON-3, 347, TOF-139) and (E)-4-cyano stilbene (25, Cat-13 A, 73.4%, TON-4, 111, TOF-171)21. 2-Bromopyridine and 2-chloro-pyridine, which were shown to give low yields or no reaction under different conditions, reacted with ethyl acrylate catalyzed by palladacycle (Cat-9) to give the 2-pyridyl ethyl acrylate (26, 68%, compared to Pd(OAc)2-50%)13g,h,21. Under other conditions described elsewhere, 2,2bipyridine (48%) was formed with recovery of starting material and no Mizoroki-Heck reaction product. {IrCl(COD)}2 and Cy-DAB catalyzed the reaction of 4-iodoanisole with ethyl acrylate to give 75% yield of the E-cinnamate. Low yields of the Mizoroki-Heck reaction products were obtained with Ni, Mn and Cu salen catalysts. These results can be compared with the reaction of 4-iodoanisole and 4iodo nitrobenzene with ethyl acrylate, catalyzed by PdCl2{P(C6H5)3}2, to give 90% E-4-methoxy ethyl cinnamate and 40% E-4-nitroethylcinnamate (27)21. While the DMG, picolinic acid, salen, 8-hydroxyquinoline were active only for aryl iodides, DAB ligands could activate aryl bromides. In comparison, the palladacycles of oxime and amines showed higher reactivity probably due to the greater stability of the 5-membered ring and the covalent bond of Pd to the aromatic ring. The use of phosphines, phosphites and N-heterocyclic carbenes as additional ligands in the palladacycles resulted in greater stability of the complexes and only slightly increased reactivity. The ferrocenyl palladacycles (Cat-11, 12A, 12B) were expected to show high activity due to the electron rich ferrocenyl group which could activate the complex by increasing the electron density at the Pd, but gave only yields comparable to the other palladacycles. The PdCl2(DAB) complexes readily activate aryl bromides and chlorides. CyclohexylDAB, 4-methoxyphenyl-DAB and 2,6-diisopropylbenzene-DAB showed good activity in these Pd catalyzed reactions and the increased activity is attributed to the increase in the electron density

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Table II ⎯ PdCl2 (DAB) catalyzed reaction of aryl halides in ionic liquid S. Aryl bromide No.

Olefin

1.

C6H5Br (28)

2. 3. 4.

C6H5Br C6H5Br 4-HO.C6H4.Br (29) 1-C10H7Br

C7H12O2a C7H12O2 C5H8O2b C7H12O2 C8H8c C8H8 C5H8O2 C5H8O2

5.

1-C10H7Br

C8H8

6.

4-(CH3)2N.C6H4.Br C8H8 (30)

Catalyst

Time Yield (hr) (%)

4 5 6 7 5 7 4 4 5 6 5 7 5

24 24 20 24 24 24 24 24 24 24 31 24 48

70 68 67 45 57 35 46 67 50 85 87 55 52

6

24

57

Reaction conditions: a: ArBr (3 mmoles), Butylacrylate (3 mmoles), Na2CO3 (6 mmoles), HCOONH4 (0.1 mmole), (C4H9)4NBr (6 mmoles); Temperature ⎯ 130°C; b. ArBr (2 mmoles), Styrene (5 mmoles), HCOONa (0.147 mmoles), CH3COONa (2.4 mmoles), (C4H9)4NBr (6 mmoles), Temperature ⎯ 130°C; a: C7H12O2 ⎯ Butyl acrylate; b: C5H8O2-Ethyl acrylate; c: C8H8 ⎯ Styrene

(basicity) at the Pd due to the strong sigma donation by the basic N. But the results are only comparable to those obtained with the phosphine and phosphite ligands probably due to the greater back bonding possible with the P-ligands compared to the Nligands. The use of (C4H9)4NBr as ionic liquid solvent resulted in higher yields (Table II)19. The Cy-DAB and other DAB ligand Pd complex catalyzed the reaction of bromobenzene, 1-bromonaphthalene, electron rich 4-bromophenol and 4-bromo-N, Ndimethylaniline with butyl acrylate and styrene forming E-butyl cinnamate (28, Cat-4, 70%), Estilbene (Cat-5, 57%), E-1-naphthyl cinnamate (Cat4, 67%), E-1-naphthyl stilbene (Cat-5, 87%), 4hydroxy-E-ethyl cinnamate (29, Cat-4, 46%), and 4N, N-dimethylaminostilbene (17A, Cat-5, 52%)21. The co-catalysts (C4H9)4NBr, (C4H9)4NI, ZnCl2 and AlCl3 assist the activation of aryl bromides and chlorides giving moderate yields with the palladacycles (Cat-10). Unactivated 4-chlorotoluene reacted with styrene to give 4-methylstilbene (30, 18%-AlCl3, 28%-(C4H9)4NI). The N-ligands described are an interesting comparison with heterogeneous catalysts.

INDIAN J. CHEM., SEC B, SEPTEMBER 2005

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110-50°C. No reaction was observed with bromobenzene while 2-bromopyridine gave 16% yield of 2, 2′-bipyridine. The attempted Mizoroki-Heck reaction of 2bromo- and 2-chloro-pyridines with ethyl acrylate or styrene in the presence of a base, under various conditions, also gave 2, 2′-bipyridine in moderate to good yields and recovered starting material (13%)13g,h. On heating the mixture of 2-bromopyridine (0.790 g, 5 mmoles), ethyl acrylate (0.650 g, 6.5 mmoles), (C4H9)4NBr (0.161 g, 0.5 mmoles), K2CO3 (0.897 g, 6.5 mmoles) and Pd dimer (Cat-8, 0.00027 g, 0.0005 mmoles) for 48 hr in NMP (10 mL) at 150°C, gave after work-up 0.180 g (46%) of 2, 2′-bipyridine and 0.108 g (13%) of 2-bromopyridine. This is an alternative route to symmetrical biaryls13i. The amination of bromobenzene by morpholine was catalyzed by PdCl2(Cy-DAB) (Cat-4) in the presence of K-tert-OC4H9 as base giving only moderate yields (15-43%) of the amination product (Scheme VI; Table V). A PTC is essential for the reaction and the yield increases from 15% for (C4H9)4NBr to 43% with 18C-6. N-heterocyclic carbene palladacycle (Cat-21) also catalyzes the amination of bromobenzene by morpholine to give 30% yield of N-phenylmorpholine22,24. CoCl{P(C6H5)3}3 (Cat-23) and

Pd on different supports has been used as a catalyst for the Mizoroki-Heck reaction23. We have communicated the use of heterogeneous Ni (supported on Y-zeolite, Al2O3, TiO2, ZrO2, SiO2), Cu/Al2O3, Co/Al2O3, U-Ni-A, U-Mn-A catalysts)23. The catalysts are recyclable, though leaching is observed under the reaction conditions. The Ni catalysts show high activity for aryl iodides and no reaction with bromides compared to the above described homogeneous N-ligand Pd catalysts (Table III)20. Suzuki coupling of aryl halides with arylboronic acids is an important methodology for the synthesis of biaryls. N-heterocyclic carbene palladacycle (Cat-13 B), N, N-dibenzyl piperazine-PdCl2 (Cat-22) catalyze the reaction of phenylboronic acid with various aryl halides (Scheme V). Electron deficient and electron rich aryl bromides both gave high yields (77-99%), while electron deficient aryl chlorides, 4-nitrochlorobenzene, 4-chlorobenzonitrile gave 78% and 49% yield (Table IV)23. Symmetrical biaryls can also be synthesized by the homo coupling of aryl halides catalyzed by N-heterocycle carbene palladacycles5g. Low to moderate yields of the symmetrical biaryls were obtained from the reaction of 4-nitroiodobenzene, bromobenzene and 2-bromopyridine in the presence of Zn dust in DMF or NMP as solvent at

X B(OH) +

2

[Pd], (Cat)

K3PO4, NMP 120 oC

Scheme V ⎯ Suzuki coupling of aryl halides with phenyl boronic acid Table III ⎯ Ni, Cu, Co and Mn heterogeneous catalysis of the Mizoroki-Heck reaction Sl. No.

1.

Aryl halide

Olefin

Catalysta Ni/Al2O3 (Cat-15)

4-CH3O.C6H4.I

CH2=CH.COOCH2CH3 CH2=CH.(CH3) (COOCH3) (31) CH2=CH.C6H5 CH2=CH.COOCH2CH3

94 76 65 95

Yield% Ni/HYZeolite (Cat-16)

Cu/Al2O3 (Cat-17)

95 75 75 90

88 80 70 80

Co/Al2O3 (Cat-18)

85 NR 56 73

9 (51)b CH2=CH.(CH3) (COOCH3) (32) 24 (25)b 22 28 (19)b CH2=CH.C6H5 (33) 85 58 73 71 95 90 23 CH2=CH.COOCH2CH3 (34) 34 4-NO2.C6H4.I 16c 14c 21c CH2=CH.(CH3).(COOCH3) (35) 59c 3. CH2=CH.C6H5 (36) 60 68 66 50 a: All catalysts are 20% metal/support b: Yield in parenthesis is of the carboxylic acid; c: (C4H9)3N was used as base; Product-4NO2.C6H4.CH2.(COOCH3)C=CH2; All products were characterized by IR and 1H NMR 2.

4-Cl.C6H4.I

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

CH3 Br

CH3

CH3

H N

+

1901

CH3

N

PdCl2(Cy-DAB), (Cat-4 )

CH3

CH3

t-C4H9OK, C6H5.CH3

CH3

CH3

20 %

Scheme VI ⎯ Amination of aryl halides Table IV ⎯ Reaction of aryl halides with phenyl boronic acid Sl. No.

Aryl halide (mmoles)

Time (hr)

Catalyst (mmole)

Yield (%)

TON

24 0.0007a 43.5 1, 243 1. C6H5.I (2) (37) 2. 4-CH3O.C6H4.I (1) (38) 24 0.0012a 88.0 733.6 a 24 0.0018 80.4 224 3. 4-NO2.C6H4.I (0.5) (39) 4. C6H5.Br (2) 24 0.0007a 73.8 2, 096 24 0.001a 66.7 684 5. 4-CH3O.C6H4.I (1) a 6. 1-C10H7Br (2) (40) 14 0.0009 99.0 2, 313 7 0.001a 77.0 771 7. 4-CH3.C6H4.Br (41) 8. 4-CH3OOC.C6H4.Br (42) 6 0.0018a 85.7 471 a 19 0.001 78.0 871 9. 4-NO2.C6H4.Cl 4 0.0007a 49.0 717 10. 4-NC.C6H4.Cl (43) 24 0.0014b 25.0 185 11. C6H5Cl b 4-CH3O.C6H4.Br (1) 4 0.0027 67 12. 0.0045b 23 C6H5Cl 22 13. 1-C10H7Br 0.0027b 74 23 14. a: Catalyst-Carbene palladacycle (Cat-13 B), b: Catalyst-N, N dibenzyl piperazine PdCl2 (Cat-22), Reaction conditions: Base: K3PO4 (2 eq); Solvent: DMF; Temperature: 120°C; C6H5.B(OH)2: 1.5 eq Table V ⎯ Amination of aryl halides Sl. No.

Aryl halide

C6H5.Br (44) C6H5.Br C6H5.Br (45) C6H5.Br C6H5.Br 4-Cl.C6H4.I (46) 4-Cl.C6H5.I (47) C10H7.Br (48) 4-CH3O.C6H4.I (49) 10. C6H5.Br 11. C6H5.Br 1. 2. 3. 4. 5. 6. 7. 8. 9.

Olefin

Co-catalyst

Yield %

C4H8ONH C4H8ONH C6H14NH C4H8ONH C4H8ONH C6H14NH C4H8ONH C6H14NH C6H11NH

(C4H9)4NBr 18-C-6 18-C-6 18-C-6 18-C-6

15a 43 20 30b 22 12 35.5 12 5

C4H8ONH C4H8ONH

-

22.3c 10d

Catalyst: a-(Cat-4)-PdCl2(Cy-DAB); b-(Cat-13 B)Pd(BPO)(NHC); c-(Cat-23)-CoCl{P(C6H5)3}3; d-(Cat-25)Mo(CO)3(C5H5N)3;

Mo(CO)3(C5H5N)3 (Cat-24) also catalyzed the reaction of bromobenzene with morpholine in low yields. In this article, a variety of N-ligand Pd complexes, which catalyze the Mizoroki-Heck reaction, Suzuki coupling and the Buchwald-Hartwig aryl amination have been described. Palladacycles of oximes and amines gave the highest yields in these reactions and are comparable to the phosphine ligated Pd complexes. The aryl aminations gave only moderate yields in the presence of the same catalysts. The Nligands described, offer easy functional group electronic tuning, as well as convenient synthetic methods of preparation, compared to the phosphine ligands and hence could be very useful ligands, for various transition metal catalyzed C-C bond formation reactions. Experimental Section The aryl halides, styrene, ethyl acrylate, glyoxal, ligands, the metal complexes and catalysts were

1902

INDIAN J. CHEM., SEC B, SEPTEMBER 2005

purchased or prepared according to known procedures5,10,17. All reactions were carried out under Ar atmosphere. Insensitive reactions were carried out in air. NMP, DMSO and DMF were used as solvents and degassed by vacuum purging and flushing with argon. The reactions were monitored by TLC using GF-254 grade silica gel on glass plates. Silica gel (100-200 mesh) was used for column chromatography. Fresh round bottom flasks and stirring bars were used to prevent contamination by reactive catalysts like Pd in the studies of the other catalysts. All the reaction products are known compounds and characterized by IR (NaCl plate), 1H NMR (CDCl3 Varian 200 MHz, Bruker 300 MHz) and MS. Representative experimental procedures are described. Preparation of dimethylglyoxime palladium (II) chloride. Palladium chloride (0.179 g, 1 mmole) was refluxed in acetonitrile (10 mL) for 1 hr and to the yellow solution dimethylglyoxime (0.116 g, 1 mmole) was added and the solution refluxed for 4 hr. The orange yellow crystals were filtered and dried (0.2 g, 68%), m.p. 278-79°C; IR (cm-1, nujol): 2923, 2852, 1571, 1496, 1461, 1373, 1317, 1282, 1215, 1172, 823, 736. Anal. Calcd for C4H8Cl2N2O2Pd: C, 16.31; H, 2.64; N, 9.25. Found: C, 16.4; H, 2.7; N, 9.5%. Preparation of (bis)-8-hydroxyquinoline palladium (II). Palladium chloride 0.176 g, (1 mmole) and 8-hydroxyquinoline(0.290 g, 2 mmole) were refluxed in ethanol (10 mL) for 4 hr. The yellowish orange precipitate was filtered, washed and dried, yield 0.186 g (47%); m.p. 345-47°C; IR (cm-1, nujol): 3444, 3201, 1600, 1209, 1068, 827, 715. Anal. Calcd for C18H12N2O2Pd: C, 54.98; H, 3.45, N, 7.06. Found: C, 54.7; H, 3.04; N, 7.05%. Preparation of N,N-(bis)cyclohexyldiimine palladium chloride (II). Palladium chloride (0.176 g, 1 mmole) and cyclohexyldiimine (0.264 g, 1.2 mmoles) of were refluxed in acetonitrile (10 mL) for 0.5 hr and the yellowish orange precipitate filtered, washed and dried, yield 0.172 g (43%), m.p. 218-20°C. Anal. Calcd for C14H24Cl2N2Pd: C, 42.10; H, 6.51, N, 7.01. Found: C, 42.33; H, 6.52; N, 6.97%. Preparation of acetophenone oxime, (2-C, N)chloro-(1, 3-diphenylimidazolidin-2-ylidene)palladacycle (II). A mixture of acetophenone oxime palladacycle (0.2 g, 0.4 mmole) and 1,1′,3,3′-tetraphenyl-2,2′-biimidazolinylidene (0.16 g) was refluxed in dry m-xylene (5 mL) at 120-30°C for 2 hr. The yellow precipitate formed was filtered and dried. The

separated solid was recrystallized from dichloromethane-hexane mixture to get a yellow crystalline powder, yield, 0.131 g (33%), m.p. >230°C, 1H NMR (δ, CDCl3 200 MHz): 9.96 (s, 1 H, OH), 8.04-8.00 (m, 4 H, Ar-H), 7.5-6.6 (m, 15 H, Ar-H), 4.5-4.2 (m, 4 H, CH2), 2.26 (s, 3 H, CH3); IR (cm-1, Nujol): 3163 (ν OH), 1284 (ν C-N). Anal. Calcd for C23H22N3OClPd: C, 55.4, H, 4.5, N, 8.4. Found: C, 55.3; H, 4.53; N, 8.38%. Preparation of chloro(N, N-dimethylbenzylamine, 2-C, N) (1, 3-diphenylimidazolidin-2ylidene)palladium (II). A mixture of 0.08 g (0.147 mmoles) of N, N-dimethylbenzylamine palladacycle and 0.066 g of 1,1′,3,3′-tetraphenyl-2,2′-biimidazolinylidene was refluxed in 5 mL dry m-xylene at 12030°C for 2 hr. The solution was filtered, concentrated and recrystallized from dichloromethane-pet. ether mixture to get white microcrystalline complex; yield, 0.03 g (21%), m.p. > 200°C, IR (cm-1, Nujol): 1280 (ν 1 C-N); H NMR (δ, CDCl3 200 MHz) 8.14-6.61 (m, 14 H, Ar-H), 4.34-4.32 (m, 4 H, CH2), 3.61 (s, 2H, CH2), 2.60 (s, 6 H, N(CH3)2). Anal. Calcd for C24H26N3ClPd: C, 57.8; H, 5.26; N, 8.43. Found: C 57.92; H, 5.27; N, 8.24%. Reaction of aryl halide with olefins (Cat-1-10). 4-Iodoanisole (0.234 g, 1 mmole), ethyl acrylate (0.28 g, 3 mmoles), catalyst-1 {Pd(DMG)Cl2, 0.025 g, 0.09 mmole} and K2CO3 (0.276 g, 2 mmoles) were taken in a flask with NMP as solvent (6 mL) and the reaction mixture heated to 140°C for 6 hr. After completion of the reaction, monitored by TLC for complete consumption of the aryl halide, the reaction mixture was poured into dil. HCl (25 mL, 10% solution) and extracted with ethyl acetate (3 × 25 mL). The combined organic fraction was washed with saturated brine, dried over anhydrous Na2SO4 and concentrated on a rotary evaporator. Purification by column chromatography over silica gel (100-200 mesh) gave the 2-propenoic acid, 3-(4methoxyphenyl)-, ethyl ester 20, (80%) yield 0.165 g, m.p. 47-48.8°C lit m.p. 49-50°C)25a. 1H NMR (200 MHz, CDCl3): δ 7.68-7.61 (d, 1 H, J = 14 Hz, Ar.CH=), 7.50-7.46 (d, 2 H, J = 8 Hz, Ar-H3, H5), 6.92-6.88 (d, 2 H, J = 8 Hz, Ar-H2, H6), 6.35-6.27 (d, 1 H, J = 16 Hz, =CH.COOC2H5), 4.31-4.20 (q, 2 H, J = 8 Hz,-COOCH2), 3.84 (s, 3 H), 1.37-1.30 (t, 3 H, J = 8 Hz, COOCH2.CH3); IR (cm-1, Nujol): 2977, 2939, 2839, 1712, 1635, 1512, 1365, 1303, 1250, 1170, 1033, 979, 833, 555, 524; MS (m/z): 206, 191, 178, 161, 147, 134, 126, 118, 103, 89, 81, 77.

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

Reaction of 4-iodo anisole with ethyl acrylate catalyzed by palladacycle 8. 4-Iodoanisole (11.7 g, 50 mmoles), ethyl acrylate (10 g, 100 mmoles), K2CO3 (8.28 g, 60 mmoles) and N-methylpyrrolidinone (50 mL) were taken in a round bottomed flask and the Pd complex 8 (0.00027 g, 0.0005 mmole) was added as catalyst. The reaction mixture was heated in an oil-bath maintained at 150°C for 8 hr. The usual extractive work-up with dil. HCl followed by purification over silica gel (100-200 mesh) gave 2propenoic acid, 3-(4-methoxyphenyl)-, ethyl ester (20, 9.223 g, 88.3%, TON 89, 540, TOF 11, 192 h-1). Reaction of 1-bromonaphthalene with styrene catalyzed by Pd(Cy-DAB)Cl2 (Cat-4) (19). 1Bromonaphthalene, 5.175 g (25 mmoles), was taken in a flask and styrene (3.03 g, 30 mmoles) and 25 mL N-methylpyrrolidinone were added to it, followed by 2.49 g (30 mmoles) of CH3COONa and 0.00022 g (0.0004 mmole) of the catalyst (Cat-4). The reaction mixture was heated to 140-50°C in an oil-bath till the bromonaphthalene was completely consumed (36 hr). Dilute HCl was added to the reaction mixture and extracted with ethyl acetate (3 × 100 mL). Washing with brine, drying over anhydrous Na2SO4, concentration on a rotary evaporator and purification by column chromatography (silica gel: 100-200 mesh) gave 5.32 g (19, 92.6%, TON-61, 956, m.p. 69.9-70.9°C)17i of naphthalene, 1-[(1E)-2-phenylethenyl]-(19). 1H NMR (200 MHz, CDCl3): δ 8.28-7.14 (m, 14 H); IR (cm-1, Nujol): 1595, 1377, 1350, 1141, 1074, 1012, 968, 956, 792, 773, 754, 690; MS (m/z): 230, 215, 202, 189, 176, 152, 141, 128, 115, 107, 101, 91, 77. Reaction of bromobenzene with styrene catalyzed by Pd(dba)2/(Cy-DAB) (Cat-4A) (18). Bromobenzene (7.85 g, 50 mmoles) was taken in a flask and styrene (5.2 g, 50 mmoles), and N-methylpyrrolidinone (15 mL) were added to it followed by 7.59 g (55 mmoles) of K2CO3, 0.00011 g (0.0002 mmole) of the Cat-4A, and 0.00008 g (0.0004 mmole) of cyclohexyl DAB. The reaction mixture was heated to 140°C in an oil-bath for 48 hr. Dilute HCl was added to the reaction mixture and extracted with ethyl acetate (3 × 100 mL). Washing with brine, drying over anhydrous Na2SO4, concentration on a rotary evaporator and purification by column chromatography (silica gel: 100-200 mesh) gave 1.354 g (18, 15%, TON-37, 600)17g of benzene, 1,1'(1,2-ethenediyl)bis-(18), m.p. 122-23°C lit 124°C,25b 1 H NMR (200 MHz, CDCl3): δ 7.5-7.1 (m, 12 H, Ar-H, CH=); IR (cm-1, Nujol): 1596, 1377, 1330, 1296,

1903

1220, 1155, 1072, 1027, 963, 962, 908, 765, 692; MS (m/z): 180, 165, 152, 139, 126, 115, 102, 89, 76. Reaction of 1-bromonaphthalene with styrene catalyzed by benzophenone oxime, (2-C, N) chloro(1, 3-diphenylimidazolidin-2-ylidene)palladacycle (II) (Cat-13B) (19). 1-Bromonaphthalene, 5.175 g (25 mmoles), was taken in a flask and styrene (3.03 g, 30 mmoles), N-methylpyrrolidinone (25 mL) were added to it followed by 2.49 g (30 mmoles) of CH3COONa and 0.00022 g (0.0004 mmole) of the (Cat-13B) benzophenone oxime palladacycle carbene catalyst. The reaction mixture was heated to 140-50°C in an oil-bath till the bromo naphthalene was completely consumed (36 hr). Dilute HCl was added to the reaction mixture and extracted with ethyl acetate (3 × 100 mL). Washing with brine, drying over anhydrous Na2SO4, concentration on a rotary evaporator and purification by column chromatography (silica gel: 100-200 mesh) gave 5.32 g (92.6%, TON-61, 956) of naphthalene, 1-[(1E)-2phenylethenyl]-(19). Di-μ-chlorobis(benzophenoneoxime)dipalladium/ AlCl3 catalyzed vinylation of 4-chlorotoluene with styrene (33). Styrene (0.416 g, 4 mmoles) and 4-chlorotoluene (0.252 g, 2 mmoles) were taken in a flask and the catalyst 10 (0.01 g, 0.01 mmole), tributyl amine (0.741 g, 4 mmoles) and tetrachloroethane (10 mL) as solvent were added. The solution was cooled in an ice-bath and AlCl3 (0.266 g, 2 mmoles) was added to the reaction mixture. Refluxing for 72 hr and the usual work-up gave the benzene, 1-methyl-4[(1E)-2-phenylethenyl]-(33, 0.150 g, 39%, m.p. 120°C, lit 120°C)25c. Di-μ-chlorobis(benzophenoneoxime)dipalladium /(C4H9)4NI catalyzed vinylation of 4-chlorotoluene with styrene (33). Styrene (0.416 g, 4 mmoles), 4-chlorotoluene (0.254 g, 2 mmoles), (C4H9)4NI (0.738 g, 2 mmoles), K2CO3 (0.552 g, 4 mmoles) were taken in a flask and the catalyst 10 (0.015 g, 0.01 mmole) added to it. 1-Methylpyrrolidinone (5 mL) was then added as solvent and the reaction mixture heated to 130°C for 24 hr. Usual work-up gave the benzene, 1-methyl-4-[(1E)-2-phenylethenyl](33) (0.095 g, 28%). Reaction of 4-chlorobenzonitrile with styrene catalyzed by carbene palladacycle (13 A) (25). 4Chlorobenzonitrile (1.393 g, 10.17 mmoles) and styrene (1.709 g, 16.4 mmoles) were taken in a flask and 10 mL of N-methylpyrrolidinone added to it. NaOAc (1.098 g, 12.5 mmoles), (C4H9)4NBr (0.322 g,

1904

INDIAN J. CHEM., SEC B, SEPTEMBER 2005

1 mmole) and acetophenone oxime palladacycle carbene (13 A, 0.0009g, 0.0018 mmole) were added to it and the reaction mixture heated to 140°C for 24 hr until all the starting material was completely consumed. Water was added, extracted with ethyl acetate, the combined organic extracts washed with brine, dried over anhydrous Na2SO4 and concentrated on a rotary evaporator. Purification by column chromatography gave 1.526 g (25, 73.4%, TON-4, 111) of benzonitrile, 4-[(1E)-2-phenylethenyl]-(33). m. p. 117.4-7.7°C, lit 115-16°C)25d, 1H NMR (200 MHz, CDCl3): δ7.8-6.8 (m, 11 H, Ar-H, CH=); IR (cm-1, Nujol): 2852, 2225, 1602, 1504, 1377, 1166, 966, 873, 823, 757, 690; MS (m/z): 205, 190, 176, 165, 151, 139, 127, 113, 102, 89, 76, 63. Reaction of 4-chloroacetophenone with styrene catalyzed by carbene palladacycle (13 B) (24). 4Chloroacetophenone (1.57 g, 10.2 mmoles) and styrene (1.680 g, 16.1 mmole) were taken in a flask and 10 mL of N-methylpyrrolidinone added to it. NaOAc (1.06 g, 13 mmoles), (C4H9)4NBr (0.322 g, 1 mmole) and benzophenone oxime palladacycle carbene (13 B, 0.0023 g, 0.0023 mmole) were added to it and the reaction mixture heated to 140°C for 24 hr until all the starting material was completely consumed. Water was added, extracted with ethyl acetate, the combined organic extracts washed with brine, dried over anhydrous Na2SO4 and concentrated on a rotary evaporator. Purification by column chromatography gave 1.71 g (75.7%, TON-3, 347), (m.p. 148-50°C), lit 142°C)25e of ethanone, 1-[4-(2phenylethenyl)phenyl]-(24); 1H NMR (200 MHz, CDCl3): δ7.97-7.93 (d, 2 H, J = 8 Hz, Ar-H2, 6), 7.617.25 (m, 7 H, Ar.CH=), 7.20-7.16 (d, 2 H, J = 8 Hz, Ar-H3, 5), 2.61 (s, 3H); IR (cm-1, Nujol): 2854, 1677, 1600, 1409, 1357, 1265, 1178, 1074, 966, 867, 821, 756, 725, 692, 592; MS (m/z): 222, 207, 178, 165, 152, 139, 126, 115, 102, 96, 89, 76, 63, 57. Reaction of 4-bromo-N, N-dimethylaniline with styrene in N-methylpyrrolidinone (13 B). 4-BromoN, N-dimethylaniline (0.395 g, 2 mmoles), styrene (0.249 g, 2.4 mmoles) and K2CO3 (0.552 g, 4 mmoles) were taken in a flask and 6 mL of N-methylpyrrolidinone added to it followed by (0.01 g, 0.017 mmole) of the catalyst (Cat-6) and the reaction mixture heated to 140-50°C for 24 hr until all the starting material was completely consumed. Water was added, extracted with ethyl acetate, the combined organic extracts washed with brine, dried over anhydrous Na2SO4 and concentrated on a rotary

evaporator. Purification by column chromatography (Silica gel: 100-200 mesh) gave 0.28 g (17A, 63%, TON-73, m.p. 147.6-8.7°C)25f of benzenamine, N, Ndimethyl-4-(2-phenylethenyl)-, (E) (17A) 1H NMR (200 MHz, CDCl3): δ 7.5-7.15 (m, 9 H, Ar-H), 7.026.94 (d, J = 16 Hz, 1 H, Ar.CH=), 6.74-6.69 (d, J = 10 Hz, 1 H, C6H5-CH), 2.98 (s, 6 H, N(CH3)2); IR (cm-1, Nujol): 2923, 2852, 1604, 1519, 1461, 1352, 1222, 966, 810, 748, 690; MS (m/z): 223, 207, 193, 178, 165, 152, 128, 111, 89, 77. Reaction of bromobenzene with butyl acrylate in ionic liquid-(C4H9)4NBr (28). (C4H9)4NBr (1.932 g, 6 mmoles) was taken in a flask and bromobenzene (0.571 g, 3 mmoles), butyl acrylate (0.384 g, 3 mmoles), HCOONH4 (0.012 g, 0.2 mmole), Na2CO3 (0.636 g, 6 mmoles) and Catalyst-4 (0.012 g, 0.03 mmole) added to it. The reaction mixture was heated to 130°C for 24 hr. Usual extractive work-up followed by purification by column chromatography gave 0.430 g (70%) of the (E)-2-propenoic acid, 3-phenyl-, butyl ester (28) (TON: 70); 1H NMR (200 MHz, CDCl3): δ7.73-7.65 (d, 1 H, J = 16 Hz, Ar.CH=), 7.56-7.31 (m, 5 H), 6.49-6.41 (d, 1 H, J = 16 Hz, =CH.COOC4H9), 4.25-4.18 (t, 2 H, J = 6 Hz, -COOCH2.C3H7), 2.05 (s, 3 H), 1.80-1.35 (m, 4 H, -COOCH2.CH2.CH2.CH3), 1.01-0.93 (t, 3 H, J = 8 Hz,-COOCH2CH2CH2.CH3); IR (cm-1, Nujol): 3060, 3028, 2958, 2933, 2873, 1712, 1639, 1311, 1280, 1170, 1066, 979, 864, 767, 709, 684. Reaction of 4-bromo-N, N-dimethyl aniline with ethyl acrylate in ionic liquid-(C4H9)4NBr (17). (C4H9)4NBr (2 g, 6.2 mmoles) was taken in a flask and 4-bromo-N, N-dimethylaniline (0.395 g, 2 mmoles), ethyl acrylate (0.4 g, 4 mmoles), HCOONa (0.010 g, 0.147 mmole), NaOCOCH3 (0.196 g, 2.4 mmoles) and Catalyst-6 (0.010 g, 0.022 mmole) added to it. The reaction mixture was heated to 130°C for 15 hr. Usual extractive work-up followed by purification by column chromatography gave 0.25 g, (57.3%) of the 2-propenoic acid, 3-[4-(dimethylamino)phenyl]-, ethyl ester (17) (TON-50, m. p. 76.3-77.8°C, lit 74-5°C)25g. 1 H NMR (200 MHz, CDCl3): δ7.68-7.60 (d, 1 H, J = 16 Hz, Ar.CH=), 7.46-7.41 (d, J = 8 Hz, 2 H, Ar-H), 6.70-6.66 (d, J = 8 Hz, 2 H, Ar-H), 6.28-6.20 (d, J = 16 Hz, 1 H, Ar.CH=), 4.27-4.20 (q, 2 H, J = 6 Hz, -COOCH2.CH3), 3.03 (s, 6 H, N(CH3)2), 1.37-1.31 (t, J = 6 Hz, 3 H,-COOCH2.CH3); IR (cm-1, Nujol): 2923, 2854, 1704, 1600, 1525, 1456, 1367, 1305, 1220, 985, 813; MS (m/z): 219, 190, 174, 146, 130, 118, 102, 98, 87, 72.

IYER et al.: TRANSITION METAL CATALYZED REACTION OF ARYL HALIDES

Ni (0), Cu (I), Co (I), Rh (I), Ir (I) catalyzed vinylation of aryl iodides. The aryl iodide (0.468 g, 2 mmoles), methyl acrylate (0.344 g, 4 mmoles), K2CO3 (0.552 g, 4 mmoles) and the catalyst (0.02 mmole) were taken in a round bottomed flask. 1Methylpyrrolidinone (5 mL) was used as solvent and the reaction mixture heated to 120-50°C for 24-48 hr. After completion (monitoring by TLC), the reaction mixture was quenched with dil. HCl, extracted with ethyl acetate, the combined organic extracts washed with brine, dried and concentrated. Purification by column chromatography gave the substituted products (E-isomers) in high yields (60-98%). Cu (I) and Ni (0) catalyzed reaction of styryl bromide with ethyl acrylate. (E)-Styryl bromide (0.366 g, 2 mmoles), ethyl acrylate (0.4 g, 4 mmoles), K2CO3 (0.552 g, 4 mmoles) and the catalyst (0.02 mmole) were taken in a round bottomed flask with 1methylpyrrolidinone as solvent (5 mL) and the reaction mixture was heated to 150°C for 12-28 hr. Usual work-up and column chromatography gave the product (2E, 4E)-ethyl-5-phenyl-(2E, 4E)-2, 4pentadienoate in high yields (64-75%); IR (CHCl3, cm-1) 2981, 1708, 1625, 1448, 1367, 1175, 841, 731; 1 H NMR (200 MHz, CDCl3): δ7.6-7.3 (m, 6H), 6.956.85 (m, 2H), 6.0 (d, J = 13.0 Hz, 1 H), 4.2 (q, J = 8.0 Hz, 2 H), 1.3 (t, J = 8.0 Hz, 3 H); MS (m/z): 202 (M+, 14), 157 (17), 129 (100), 115 (7), 77 (36), 63 (18). Cu and Ni (0) catalyzed cyclization of N-methylN-allyl-2-iodobenzamide. The 2-iodobenzamide (0.602 g, 2 mmoles), K2CO3 (0.552 g, 4 mmoles), catalyst {CuI-0.038 g, 0.2 mmole, Ni{P(OC6H5)3}40.126 g, 0.1 mmole)}and 1-methylpyrrolidinone (5 mL) were heated in a round bottomed flask (5 mL) at 150°C for 48 hr to give N-methyl-4-methylisoquinolinone (0.275 g, 79% yield), after the usual work-up and purification by column chromatography, m.p. 79°C, (lit 80-2°C)25h; IR (CHCl3, cm-1): 2932, 1699, 1626, 1437, 1386, 768; 1H NMR (200 MHz, CDCl3): δ8.5 (d, J = 8.1 Hz, 1 H), 7.65-7.45 (m, 3 H), 6.9 (s, 1 H), 3.55 (s, 3 H), 2.25 (s, 3 H); 13C NMR (50 MHz, CDCl3): δ 162.4, 137.12, 131.61, 130.00, 127.73, 126.32, 125.69, 122.08, 111.64, 36.39, 15.00; Mass (m/z): 173 (M+, 100), 158 (14), 144 (38), 115 (7.5), 104 (11), 77 (4). The attempted Cu and Ni (0) catalyzed cyclization of 2-iodoallylbenzoate. The 2-iodoallylbenzoate (0.576 g, 2 mmoles), K2CO3 (0.552 g, 4 mmoles), catalyst (0.2 mmole) and 1-methylpyrrolidinone (5 mL) were heated in a round bottomed flask (5 mL) at

1905

150°C for 18-24 hr. After the usual work-up only the dehalogenated and deallylated products were isolated. MnO2 catalyzed vinylation of 4-iodoanisole. 4Iodoanisole (0.468 g, 2 mmoles), ethyl acrylate (0.4 g, 4 mmoles), K2CO3 (0.552 g) and the MnO2 (0.174 g, 0.2 mmole) were heated in 1-methylpyrrolidinone at 150°C for 24 hr to give (E)-4-methoxyethylcinnamate in 80% yield (0.41g). Reaction of 2-chloropyridine with ethyl acrylate. 2-Chloropyridine (0.228 g, 2 mmoles), ethyl acrylate (1.1 g, 10 mmoles), (C4H9)4NBr (0.64 g, 2 mmoles) and K2CO3 (0.552 g, 4 mmoles) were taken in a flask and Pd(OAc)2 (0.023 g, 0.1 mmole) and triphenylphosphine (0.052 g, 0.2 mmole) were added followed by 1-methylpyrrolidinone (5 mL). The reaction mixture was heated to 150°C for 4 hr. Usual work-up and purification by column chromatography gave ethyl-3-(2-pyridyl)-(E)-2-propenoate (oil, 0.14 g, 50%); IR (Neat, cm-1): 2983, 2854, 1705, 1620, 1043, 944, 776; 1H NMR (200 MHz, CDCl3): δ 8.55-8.50 (m, 1H), 7.6 (m, 1H), 7.55 (d, J = 17.0 Hz, 1 H), 7.3 (d, J = 6.0 Hz, 1 H), 7.2-7.1 (m, 1 H), 6.8 (d, J = 17.0 Hz, 1 H), 4.2 (q, J = 7.4 Hz, 2 H), 1.34 (t, J = 7.5 Hz, 3 H); 13C NMR (50 MHz, CDCl3): δ166.78, 153.20, 150.30, 143.47, 136.90, 124.34, 124.23, 122.66, 60.72, 14.42; Mass (m/z): 173 (M+, 100), 158 (14), 144 (38), 115 (7.5), 104 (11), 77 (4). Heterogeneous catalysis: (a) Ni/Al2O3 catalyzed reaction of iodobenzene with ethylacrylate. Iodobenzene (0.204 g, 1 mmole), ethyl acrylate (0.5 g, 5 mmoles), K2(CO)3 (0.276 g, 2 mmoles), catalyst (20% Ni/Al2O3, 0.025 g) and 1-methylpyrrolidinone (5 mL) were taken in a flask and heated to 150°C. The reaction was complete in 2 hr and the usual work-up and purification gave the E-ethyl cinnamate (0.167 g, 95%). Palladacycle (Cat-21) catalyzed Suzuki reaction of phenylboronic acid with 4-chloronitrobenzene. 4-Chloronitrobenzene (0.157 g, 1 mmole), phenyl boronic acid (0.180 g, 1.5 mmoles), K3PO4 (0.460 g, 2 mmoles), catalyst (Cat-21, 0.0005 g, 0.0009 mmole} and (C4H9)4NBr (0.161 g, 0.5 mmole) were taken in a round bottomed flask with N, N-dimethylformamide (5 mL) as solvent and the reaction mixture heated to 120°C for 19 hr. After completion (monitoring by TLC), the reaction mixture was quenched with dil. HCl, extracted with ethyl acetate, the combined organic extracts washed with brine, dried and concentrated. Purification by column chromatography gave 0.156 g of 4-nitrobiphenyl (78%, TON-871) m.p. 113.7°C, lit 114-14.5°C)25; IR (Nujol, cm-1):

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INDIAN J. CHEM., SEC B, SEPTEMBER 2005

2952, 2923, 2854, 1928, 1598, 1573, 1504, 1463, 1352, 1078, 852, 775, 740, 698; 1H NMR (200 MHz, CDCl3): δ 8.25-8.20 (d, J = 10 Hz, 2 H), 7.67-7.63 (d, J = 8 Hz, 2 H), 7.60-7.25 (m, 5 H); 13C NMR (50 MHz, CDCl3): δ 147.17, 147.5, 138.72, 129.09, 128.83, 127.62, 127.28, 123.98, 96.15; Mass (m/z): 199 (M+), 169, 152, 141, 126, 115, 102, 87, 74, 63. Reaction of bromobenzene with morpholine. Bromobenzene (0.314 g, 2 mmoles), morpholine (0.174 g, 2 mmoles), K-t-(OC4H9) (0.225 g, 2.2 mmoles), PdCl2(DAB) (0.010 g, 0.025 mmole) and 18-C-6 (0.1 g, 0.38 mmole) were taken in a flask containing toluene (10 mL) and the mixture refluxed for 24 hr. The reaction mixture was concentrated on a rotary evaporator, added water and extracted with ethyl acetate, dried and concentrated. The product was purified by column chromatography to give 0.140 g of N-phenylmorpholine (42.9%); IR (Nujol, cm-1): 3010, 2966, 2858, 2825, 1598, 1498, 1450, 1379, 1232, 1120, 927, 756; 1H NMR (200 MHz, CDCl3): δ 7.357.20 (m, 2 H), 6.95-6.85 (m, 3 H), 3.89-3.84 (m, 4 H), 3.18-3.13 (m, 4 H).

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Acknowledgement Authors thank the DST, New Delhi, for research funds. Also, the author (CR, GMK) thank the CSIR, New Delhi for SRF′s and D K Kashinath, A Jayanthi, V V Thakur and S Subramaniam for some preliminary experiments. References and Notes 1 (a) Heck R F, Comprehensive Organic Synthesis, Vol-4, edited by, B M Trost & I Fleming, (Pergamon Press, Oxford), 1991, 833. (b) Heck R F, Acc Chem Res, 12, 1979, 146. (c) Heck R F, Organic Reactions, 27, 1982, 345. (d) de Meijere A & Meyer F E, Angew Chem Int Ed Engl, 33, 1994, 2379. (e) Hieringer W, Applied Homogeneous Catalysis with Organometallic Compounds Vol-2, 2nd Edn.) 721. edited by B Cornils and W A Herrmann, (Wiley-V C H Verlag GmbH: Weinheim, Germany) 2002. (f) Woltermann C J, Pharma Chem, 1(1/2), 2002, 11. (g) Frost C G, Rodd's Chemistry of Carbon Compounds, 2nd Edn, Vol 5, edited by M Sainsbury, (Elsevier: Amsterdam, Neth. English) 2001, 315. (h) Eisenstadt A & Ager D J, Fine Chemicals through Heterogeneous Catalysis, edited by R A Sheldon & H Van Bekkum, (Wiley-VCH Verlag GmbH: Weinheim, Germany) 2001, 576. (i) Eisenstadt A, Catalysis of Organic Reactions, 1998, 415. (j) Beletskaya I P, Kashin A N, Karlstedt N B, Mitin A V, Cheprakov A V & Kazankov G M, J Organomet Chem, 622 (1-2), 2001, 89.

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(g) Prager B, Jacobson P, Schmidt P, Stern D Beilstein, 14, 522, 1931, (Springer-Verlag, Berlin). (h) H-0-02943, Dictionary of Organic Compounds, Vol 4, 6th edn, (Chapman & Hall, London, UK), 1996, 3709. 26 Registry numbers of the products: 1. 2-Propenoic acid, 3-(4chlorophenyl)-, ethyl ester, (E) (14) (24393-52-0) 2. 2Propenoic acid, 3-phenyl-, ethyl ester, (2E) (15) (4192-77-2) 3. Phenol-4-(2-phenylethenyl-(16)-(3839-46-1) 4. 2-Propenoic acid-3-[4-(dimethylamino)phenyl]-, ethyl ester (17) (155297-2) 5. Benzene, 1, 1'-(1, 2-ethenediyl)bis-(18) (103-30-0) 6. Naphthalene, 1-[(1E)-2-phenylethenyl]-(19) (2840-87-1) 7. 2Propenoic acid, 3-(4-methoxyphenyl)-, ethyl ester (20) (192930-2) 8. 2-Propenoic acid-3-(1-naphthalenyl)-, ethyl ester, (E)-(21) (98978-43-9) 9. Benzene, 1-methoxy-4-[(1E)-2phenylethenyl]-(22) (1694-19-5) 10. Benzene, 1-nitro-4[(1E)-2-phenylethenyl (23) (1694-20-8) 11. Ethanone, 1-[4(2-phenylethenyl)phenyl]-(24) (3112-03-6) 12. Benzonitrile, 4-[(1E)-2-phenylethenyl]-(25) (13041-79-7) 13. 2-Propenoic acid, 3-(2-pyridinyl)-, ethyl ester, (2E)-(26) (70526-11-3) 14. 2-Propenoic acid, 3-(4-nitrophenyl)-, ethyl ester (27) (953-264) 15. Propenoic acid, 3-phenyl-, butyl ester (28) (538-65-8) 16. 2-Propenoic acid-3-(4-hydroxyphenyl)-, ethyl ester (29) (2979-06-8) 17. Benzenamine, N, N-dimethyl-4-(2-phenylethenyl)-, (E) (17A) (838-95-9) 18. Benzene, 1-methyl-4[(1E)-2-phenylethenyl]-(30) (1860-17-9) 19. C12H14O3-2-Propenoic acid-3-(4-methoxyphenyl)-2-methyl-methylester-(31) [30780-60-0] 20. C11H11ClO2-2-Propenoic acid-3-(4chlorophenyl)-2-methylmethyl ester-(32) [53059-73-7] 21. Benzene-1-chloro-4-[(1E)-2-phenylethenyl](33) (1657-50-7) 22. 2-Propenoic acid, 3-(4-chlorophenyl)-, ethyl ester-(34)(6048-06-22) 23. 2-Propenoic-2-methyl-3-(4-nitrophenyl)(35)-(40277-76-7) 24. 1, 1'-Biphenyl-(36)-(92-52-4) C12H10 25. C13H13O2-1, 1-Biphenyl-4-methoxy-(37)- [613-37-6]-26. 1, 1'-Biphenyl, 4-nitro-(38)-(92-93-31)-C12H9NO2 27. C16H12[605-02-7]-(39)-Naphthalene-1-phenyl 28. C13H13-1, 1-Biphenyl-(4)-methyl-(40) [644-08-6] 29. C14H13O2-(41)-[720-75-2]1, 1-Biphenyl-4-carbomethoxy 30. C13H9N-1, 1-Biphenylcarbonitrile-(42)-[2920-38-9] 31. Morpholine-4-phenylC10H13NO-(43)-(92-53-5) 32. (4107-98-6)-(44)-Benzenamine, N,N-bis(1-methylethyl)-C12H19N 33. C12H19ClN-(45)-Benzenamine-4-chloro-N, N-bis(1-methylethyl)-[126086-73-5] 34. C10H12ClNO-Morpholine-4-(4-chlorophenyl)-(46)-[70291-677] 35. C16H21N-1-Naphthalenamine-N, N-bis(1-methylethyl)(47)-[4960-24-1] 36. C13H19NO-Benzenamine-N-cyclohexyl4-methoxy-(48)-[780-02-9]; 37. 2-Propenoic acid, 3-(4cyanophenyl)-, ethyl ester, (E)-(37) (62174-99-6) 38. 2Propenoic acid, 3-(4-acetylphenyl)-, ethyl ester, (E) (38) (82989-26-2) 39. Cat-13 B-Palladium, chloro-(1, 3-diphenyl2-imidazolidinylidene)[2[(hydroxyimino)-phenylmethyl]phenylC,N]-, (SP-4-4)-C28H24ClN3OPd–(68248-78-2) 40. Cat-10Palladium, di-μ-chlorobis [2-[1-(hydroxyimino) ethyl]phenylC, N]di, stereoisomer--C16H16Cl2N2O2Pd-(32679-19-9) 41. Cat-8 Palladium, di-μ-chlorobis[2-[(dimethylamino-N)methyl]phenyl-C]di-C18H24Cl2N2Pd2-(18987-59-2) 42. Cat-13 A-Palladium, chloro-(1,3-diphenyl-2-imidazolidinylidene)[2-[1-(hydroxyimino)ethyl]phenyl-C, N]-, (SP-4-4)-C23H22ClN3OPd-(6824877-1) 43. Cat-13 B-Palladium, chloro-(1, 3-diphenyl-2imidazolidinylidene)[2-[(hydroxyImIno)phenylmethyl]phenylC, N]-, (SP-4-4)-C28H24ClN3OPd-(68248-78-2) 44. Cat-13C Palladium, chloro-[2-[(dimethylamino)methyl]phenyl-C, N](1, 3-diphenyl-2-imidazolidinylidene)-, (SP-4-4)-C24H26ClN3Pd(68248-79-3).