Selectivity in the Aliphatic Palladation of Ketone Hydrazones. An

Organometallics 1995, 14, 4427-4430

4427

Selectivity in the Aliphatic Palladation of Ketone Hydrazones. An Example of Palladium-Promoted Intramolecular Addition of a Nfl-Dimethylhydrazone to an Alkene Diego J. Cardenas and Antonio M. Echavarren" Departamento de Quimica Organica, Universidad Autbnoma de Madrid, Cantoblanco, 28049 Madrid, Spain Received March 28, 1995@ Summary: The effcacy of the aliphatic palladation reaction diminishes with the nucleophilicity of the hydrazone imino nitrogen; no benzylic or allylic C-H activation was observed. A y,d-unsaturated dimethylhydrazone reacts with Pd(PPhdzC12 to yield a palladacycle resulting from the addition of the imino group to a (+alkene)palladium complex. Introduction We have recently reported the aliphatic palladation of N,N-dimethylhydrazones with Pd(PPh&C12 or Pd(AsPh&C12 (eq 11.l The palladation proceeds in the

presence of sodium acetate in acetonitrile at 65-75 "C t o give the desired five-membered palladacycles. This aliphatic palladation process2 takes place regioselectively on the least-substituted a position of the hydrazone and leads to stable five-membered ring metallacycles which do not decompose by ,&hydride elimination. Although the mechanism of this reaction was not determined in detail it was shown that the palladium(11) complex coordinates first with the imino nitrogen and that the addition of acetate promotes the formation of the palladacycle. In this context, it is of interest to note a recent report on the activation of the benzylic positions of toluene and p-xylene with Pd(PPh&C12 and related bromo and iodopalladium(I1)c~mplexes.~ Even more remarkably, simple alkanes such as hexane and cyclohexane were activated with these palladium(I1)complexes at 70- 130 0C.3 Although the aliphatic palladation reaction was shown to proceed satisfactorily with the examined N,Ndimethylhydrazones,l we wished to determine more precisely the scope and limitations of this process. In particular, it was of interest to examine the palladation of substrates possessing benzylic4 and allylic5C-Hthat could be activated by the palladium(I1) reagent. Additionally, we also studied the possible extension of the @Abstractuublished in Advance ACS Abstracts. Julv 1. 1995. (1)Cardenas, D. J.; Echavarren, A. M.; Vegas, A. 0;ganometallics 1994. _ _ -, I,?. - - , 882. -~~ (2)For recent references, see the following: Yoneda, A.; Hakushi, T.; Newkome, G. R.; Fronczek, F. R. Organometallics 1994,13,4912 and references therein. (3)Vedernikov, A. N.;Kuramshin, A. I.; Solomonov, B. N. J. Chem. SOC.,Chem. Commun. 1994,121. ~

Chart 1 NNX

1

2 : X = NMePh 3 : X = NPh2 4 : X = NHPh 5 : X = N-N=C(Me)Ph 6:X=OH 7 : X = OMe

& & N-NMe2

NINMe2

9

10 Me2N.N

C=S/"*NMe2

An/

R

11

12 : R = Me 13 : R = Ph

palladation reaction t o other N-directing groups and the application to N,N-dimethylhydrazones of some cyclic ketones. In this paper we report the results of a study on the reactions of substrates 1-13 (Chart 1)with Pd(PPh&C12 and the first example of an intramolecular attack of the imino nitrogen of a hydrazone to an alkene promoted by p a l l a d i ~ m . ~ , ~ (4) Benzylic palladation: (a) Hartwell, G. E.; Lawrence, R. V.; Smas, M. J. J.Chem. SOC.,Chem. Commun. 1970,912.(b) Dehand, J.;Motet, C.; Pfeffer, M. J. Organomet. Chem. 1981,209,255.(c) Garber, A. R.; Garrou, P. E.; Hartwell, G. E.; Smas, M. J.; Wilkinson, J. R.; Todd, L. J. J . Organomet. Chem. 1975,86,219. (d) Steel, P. J.; Caygill, G. B. J . Organomet. Chem. 1987,327,101.(e) Deeming, A.J.; Rothwell, I. P. J . Chem. Soc., Chem. Commun. 1978,344.(0 Deeming, A. J.;Rothwell, I. P. J. Chem. SOC.,Dalton Trans. 1978, 1490. (g) Deeming, A. J.; Rothwell, I. P.; Hursthouse, M. B.; Malik, K. M. A. J . Chem. SOC., Dalton Trans. 1979,1899.(h) Ryabov, A. D. J . Organomet. Chem. 1984, 268,91.(i) Pfeffer, M.;Wehman, E.; van Koten, G. J. Organomet. Chem. 1985,282, 127. Newkome, G. R.; Evans, D. W. Organometallics 1987,6,2592. (k) Ryabov, A.D.; Yatsimirsky, A. K. Inorg. Chem. 1984, 23,789.(1) Albert, J.; Granell, J.; Sales, J.; Solans, X.; Font-Altaba, M. Organometallics 1986,5,2567. (m)Albert, J.; Ceder, R. M.; Gbmez, M.; Granell, J.; Sales, J. Organometallics 1992,11, 1536.(n) Barro, J.; Granell, J.; Sainz, D.; Sales, J.; Font-Bardia, M.; Solans, X. J. Organomet. Chem. 1993,456,147, (5)(a) Chrisope, D. R.; Beak, P. J . Am. Chem. SOC.1986,108,334. (b) Chrisope, D. R.; Beak, P.; Saunders, W. H. J. Am. Chem. SOC.1988, 110,230 and references therein. (6) Hegedus, L. S. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991;Vol. 4,Chapter 3.1.

0276-7333/95/2314-4427$09.00IQ 0 1995 American Chemical Society

Notes

4428 Organometallics, Vol. 14,No. 9, 1995

Scheme 1

Chart 2 Me, Me

,.Me N N’ \ /CI

Ph,N,..Me N’ \

/CI

t~le2N.~

&

Me pd\PP h3

e p d \ P P h3 12

14

15

Me,

Pd(PPh3)2C12 NaOAc,MeCG

Me,, ,Me CI, ,N-N P Ph3P’

d

h

17

+

.,Me

NSN\

,CI

@“\PPh3 16

Results and Discussion Hydrazone 1,obtained as a mixture of diastereomers, possesses three potentially reactive sites: aromatic, benzylic, and a-methyl. Reaction of 1 with Pd(PPh3)pCl2 and NaOAc in acetonitrile a t 70 “C led exclusively to the formation of palladacycle 14 (Chart 2), isolated in 57% yield, as a result of the regioselective activation of the methyl a to the hydrazone function. None of the alternative palladation products was detected in the crude reaction mixture. On the other hand, N-methylN-phenylhydrazone 2 reacted with Pd(PPh3)zClzto give 15 as the only palladacycle. None of the alternative palladacycle derived from activation of the N-phenyl group could be observed. However, 15 was isolated in a lower yield (42% yield) than that obtained in the palladation of the corresponding N,N-dimethylhydrazone (97%).l This lower yield is consistent with the lower basicity, and increased steric hindrance, of the N-directing group of 2. Accordingly, N,N-diphenylhydrazone 3 failed to yield a palladation product with Pd(PPh3)zClz. A similar result was obtained with hydrazone 4,azine 5,oxime 6,and methoximes 7 and 8. In this last experiment, /3-palladation, a known reaction with a,a-disubstituted oximes,6was not observed. It is of interest to note that in none of these experiments was aromatic palladation observed, in spite of the known activating effect of these functional group^.^ These results provide further support that the coordination of triphenylphosphine considerably reduces the electrophilicity of palladium(II), leading t o intermediate complexes which are unable to activate aromatic positions. By reaction with Pd(PPh3)zCl~under the usual reaction conditions, camphor and quinuclidinonehydrazones (7) For the palladium-mediated intramolecular reaction of amines with alkenes leading to allylic functionalization, see the following: van der Schaaf, P.; Sutter, J.-P.; Grellier, M.; van Mier, G. P. M.; Spek, A. L.; van Koten, G.; Pfeffer, M. J . Am. Chem. SOC.1994,116,5134and references therein. (8)(a)Constable, A. G.; McDonald, W. S.; Sawkins, L. C.; Shaw, B. L. J. Chem. Soc., Chem. Commun. 1978,1061.(b) Constable, A. G.; McDonald, W. S.; Sawkins, L. C.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1980,1992.(c) Carr, K.; Sutherland, J. K. J . Chem. Soc., Chem. Commun. 1984,1227.(d) Baldwin, J. E.; Ntijera, C.; Yus, M. J . Chem. Soc., Chem. Commun. 1986, 126. (e) Baldwin. J. E.: Jones. R. H.: Najera, C.; Yus, M. Tetrahedron 1986,41,699. (0 Rocherolle, V.;Upez, J. C.; Olesker, A.; Lukacs, G. J . Chem. Soc., Chem. Commun. 1988, 513.(g) Wells, A. P.; Etching, W. Organometallics 1992,11, 2750. (9)Reviews: (a) Dehand, J.; Pfeffer, M. Coord. Chem. Rev. 1976, 18, 327.(b)Newkome, G. R.; Puckett, W. E.; Gupta, V. K.; Kiefer, G. E. Chem. Rev. 1986,86,451. (c) Omae, I. Coord. Chem. Rev. 1988,83, 137.(d) Dunina, V.V.; Zalevskaya, 0. A.; Potapov, V. M. Russ. Chem. Rev. 1988,57,250.(e) Ryabov, A. D. Chem. Reu. ISSO,90,403.

18

9 and 10 gave rise to complex reaction mixtures, presumably containing coordination complexes. However, no aliphatic palladation products were obtained from 9 or 10,even under forcing conditions. The failure with these rigid bicyclic substrates may be due to the unfavorable angle between the methylene C-H and the hydrazone, since cyclohexanoneN,N-dimethylhydrazone (11)furnished palladacycle 16. In this case, the isolated yield was low (36%)due to partial decomposition of the palladacycle under the reaction conditions. 5-Hexen-2-oneN,N-dimethylhydrazone(121,prepared as a mixture of E and Z diastereomers, was also examined t o determine whether the allylic activation could compete with the usual pathway to form a (r3allyl)palladium(11) complex or, alternatively, t o a sixmembered (ql-allyl)palladium complex with the metal coordinated to the amino nitrogen. However, 12 reacted with Pd(PPh&C12 at 65 “C to give a mixture of two palladacycles which could be separated by column chromatography (Scheme 1). The minor product, isolated in 17% yield, was the expected palladacycle 17 resulting from the palladation on the least-substituted p0sition.l Surprisingly, the polar derivative 18 was obtained as the major product. This derivative showed two doublets in the lH NMR spectrum at 3.07 ppm (J = 2.5 Hz) and 3.03 ppm (J = 2.0 Hz), corresponding to the diastereotopic N-methyls coupled to 31P. In the 13C NMR spectrum a low-field signal was observed at 208.33 ppm and was assigned to an iminium carbon. This resonance is shified almost 29 ppm downfield as compared with the hydrazone carbon of 17. The observation of a CH carbon at 61.13 ppm is also consistent with the cationic structure for 18. Complex 18 is probably formed by a palladium-promoted attack of the imino nitrogen of 12 on the alkene, followed by coordination of the amino nitrogen of the hydrazone to palladium (Scheme 1). Nucleophilic additions of amines to alkene palladium complexes are p r e ~ e d e n t e d ,although ~?~ this is to our knowledge the first example of a reaction of a hydrazone as the nucleophile.lOJ1Surprisingly, related hydrazone 13 was recovered unchanged under the conditions of Scheme 1, probably as a consequence of the diminished nucleophilicity of its imino nitrogen. The failure to obtain a palladation product on the methylene a to the hydrazone of 13 is also somewhat surprising, (10)For a n imine addition to a n alkene iron(I1) complex, see the following: Berryhill, S. R.; Price, T.; Rosenblum, M. J . Org. Chem. 1983,48, 158. (11)For the unrelated zirconium-promoted intramolecular addition of hydrazones to alkynes, see the following: Buchwald, S. L.; Wannamaker, M. W.; Watson, B. T. J . Am. Chem. SOC.1989,111, 4495.

Organometallics, Vol. 14, No. 9, 1995 4429

Notes since the related NJV-dimethylhydrazone of propiophenone furnished the corresponding palladacycle uneventfully.1

Conclusions This study reveals that the efficacy of the aliphatic palladation reaction diminishes, as expected, with the nucleophilicity of the hydrazone imino nitrogen. The failure of rigid bicyclic hydrazones 9 and 10 suggests that a planar arrangement of the C-H and the hydrazone is required for the palladation reaction to proceed under normal conditions as has been demonstrated before in the benzylic C-H activation of methylquinoline^.^^ Under the conditions developed for this palladation reaction, no benzylic or allylic C-H activation was observed. However, the y,b-unsaturated dimethylhydrazone 12 leads to the formation of palladacycle 18,a rare example of addition of an imino group to a (q2-alkene)palladiumcomplex.

Experimental Section General Procedures. All reactions were carried out under an atmosphere of Ar. Solvents were dried before use by standard methods. Pd(PPh3)Clz was prepared by a known method.12 The following hydrazones were prepared from the corresponding ketones according t o known procedures: 142methylpheny1)-1-ethanoneN,N-dimethylhydrazone ( 1),13acetophenone N-methyl-N-phenylhydrazone (2),14acetophenone N,N-diphenylhydrazone (3),15acetophenone N-phenylhydraacetophenone oxime zone (4),16"acetophenone azine (5),16b (6),16cacetophenone methoxime (7),17propiophenone methoxime (@,I7 (+)-camphor N,N-dimethylhydrazone (9),18and cyclohexanone N,N-dimethylhydrazone (1l L l g Quinuclidinone NJV-Dimethylhydrazone (10). A mixture of quinuclidinone hydrochloride (860 mg, 5.94 mmol), NaOAc (487 mg, 5.94 mmol), and N,N-dimethylhydrazine (1.4 mL, 18.1mmol) in EtOH (15 mL) was heated under refluxing conditions for 48 h. After the solution had been cooled to room temperature, the solvent was evaporated and the residue was suspended in EtOAc and filtered. The filtrate was evaporated, dissolved in EtZO, dried (MgSOd),and evaporated to give 11 as a greenish oil (592 mg, 51%) as a mixture of E and 2 isomers. 'H NMR (200 MHz, CDC13) 6 3.78 (s, 2H), 3.02 (m, 4H), 2.68 (m, lH), 2.45 (s, 3H), 2.00 (s, 3H), 1.94 (m, 4H); {'H} NMR (50 MHz, CDC13) 6 175.13, 169.77, 52.22", 46.34, 45.36, 30.74*, 24.19*, 21.57* (the ''w' denotes overlapping signals for both isomers). 5-Hexen-2-oneNJV-Dimethylhydrazone(12). 5-Hexen2-one (1.67 g, 17 mmol) and N,N-dimethylhydrazine (1.7 mL, 22.1 mmol) in toluene (25 mL) containing a catalytic amount of p-toluenesulfonic acid monohydrate (ca. 5 mg) was heated with azeotropic removal of water (Dean-Stark apparatus) for 24 h. After the mixture had been cooled to room temperature, it was diluted with Et20 (50 mL), washed with water (3x1, dried (MgS04),and evaporated to give 12 as an oil (88:12 (12) (a) Gmelin Handbuch der Anorganischen Chemie; SpringerVerlag: Weinheim, Germany; 1924; Palladium, Vol. 65. (b) Colquhoun, H. M.; Holton, J.; Thompson, D. J.; Twigg, M. V. New Pathways for of Transition Metals; PleOrganic S-ynthesis. Practical Applications -. num: New York, 1984. (13)Newkome, G. R.; Bhacca, N. S. J. Org. Chem. 1971, 36, 1719. (14) Karabatsos. G. J.: Krumel. K. L. Tetrahedron 1967.23, 1097. (15) Sharma, S. D.; Pandhi, S. B. J. Org. Chem. 1990,55, 2196. (16) (a) Vogel, A. Vogel's Texbook of Practical Organic Chemistry, 4th ed.; Longman: London, 1978; p 1112; (b) Ibid., p 1114; (c) Ibid., p 1113. (17) Karabatsos, G. J.; Hsi, N. Tetrahedron 1967,23, 1079. (18) Chelucci, G.; Delogu, G.; Gladiali, S.; Soccolini, F. J. Heterocycl. Chem. 1986,23, 1395. (19) Newkome, G. R.; Fishel, D. L. J. Org. Chem. 1966,31,677.

mixture of E and 2 isomers). The crude product (quantitative yield) was sufficiently pure and was not purified. E isomer: 'H NMR (200 MHz, CDC13) 6 5.82 (ddt, J = 16.9, 10.4,6.3 Hz, lH), 5.04 (m, 2H), 2.43 (8, 6H), 2.30 (m, 4H), 1.95 (s, 3H); {'H} NMR (50 MHz, CDC13) 6 166.08, 136.72, 114.33, 46.30 (2C), 37.44, 30.40, 15.98. 2 isomer: IH NMR (200 MHz, CDC13) 6 5.82 (m, lH), 5.05 (m, 2H), 2.41 (s, 6H), 2.28 (m, 4H), 1.93 (s, 3H); W i l H } NMR (50 MHz, CDC13) (only distinct signals) 6 168.04, 46.74 (2C), 29.74. 1-Phenyl-4-penten-1-oneN&-Dimethylhydrazone (13). To a solution of acetophenone NJV-dimethylhydrazone (675 mg, 4.16 mmol) in THF (5 mL) at -78 "C was added BuLi (2.6 mL, 1.6 M solution in hexane, 4.16 mmol). The mixture was slowly warmed up t o -45 "C (ca. 1 h), and allyl iodide (0.38 mL, 4.16 mmol) was added. After 15 min at -45 "C the mixture was warmed up t o 0 "C. After it had been stirred at this temperature for 1h, the mixture was treated with aqueous NH&l (saturated solution, pH 8, 5 mL). The aqueous phase was extracted with EtzO, and the combined organic extracts were washed with water (3x) and dried (MgS04). The solvent was evaporated, and the residue was filtered through silica gel ( 1 O : l hexane-EtOAc) t o give 13 as a greenish oil (735 mg, 87%): 'H NMR (200 MHz, CDC13) 6 7.62 (m, 2H), 7.37 (m, 3H), 5.81 (ddt, J = 17.0, 10.3, 6.5 Hz, lH), 4.99 (m, 2H), 2.99 (m, 2H), 2.56 (s, 6H), 2.20 (m, 2H); 13C{1H}NMR (50 MHz, CDC13) 6 166.94,137.05,136.60, 128.55,127.60, 126.33,114.32, 47.12 ( 2 0 , 30.53, 26.81. Aliphatic Palladation: General Procedure. A mixture of hydrazone (0.1-0.2 mmol), NaOAc (1equiv), and Pd(PPh3)zClz (1equiv) in acetonitrile (6-10 mL) was heated at 65-75 "C for 24-48 h. The originally yellow suspension usually remains unchanged, although in some instances an orange suspension or a solution was obtained. After it had been cooled t o room temperature, the solvent was evaporated and the residue was chromatographed (flash grade silica gel) to yield the palladacycle as a pale yellow solid. Heating under reflux conditions or the use of impure hydrazone as the starting material led t o lower yields and formation of metallic palladium. Palladacycle 14. Reaction conditions: 70 "C, 15 h. Eluent: 3:l hexane-EtOAc. Yield: 57%. 'H NMR (300 MHz, CDC13) 6 7.72 (m, 6H), 7.41 (m, 9H), 7.09 (m, 4H), 3.18 [d, 4J(1H-31P) = 2.4 Hz, 6H], 2.50 [d, 3J('H-31P) = 3.5 Hz, 2H1, 2.23 (s, 3H); W{'H} NMR (50 MHz, CDC13; DEPT) 6 178.87 [d, 3J(13C-31P)= 3.6 Hz; C], 135.14 (C), 134.46 [d, 2J('3C-31P) = 11.7 Hz, PPh3; CHI, 130.96 [d, 1J(13C-31P)= 49.2 Hz, PPh3; C], 130.52 (CH), 130.45 [d, 4J(13C-31P)= 2.3 Hz, PPh3; CHI, 128.57 (CH), 128.17 [d, 3J(13C-31P)= 10.5 Hz, PPh3; CHI, 127.32 (CHI, 125.49 (CH), 51.51 [d, 3J('3C-31P) = 2.0 Hz, 2 CH3],42.49 [d, 2J(13C-31P)= 4.7 Hz, CH21, 20.05 (CH3) (one carbon signal was not observed); 31P{1H}(121.4 MHz, CDC13) 6 33.50; IR (KBr)3040 (w), 2900 (w), 1605 (m), 1475 (SI, 1440 (SI, 1430 (SI, 1380 (m), 1285 (m), 1175 (m), 1090 (SI, 1000 (SI, 935 (s), 745 (SI, 720 (SI, 690 (SI, 525 (SI, 425 (m); HRMS m l z calcd for CzgH3&1N2PPd, 578.0870; found 578.0865. Anal. Calcd for C29H30ClNzPPd: C, 60.12; H, 5.22; N, 4.83. Found: C, 60.40; H, 5.50; N, 4.87. Palladacycle 15. Reaction conditions: 65 "C, 44 h. Eluent: 3:l hexane-EtOAc. Yield: 42%. 'H NMR (300 MHz, CDC13)6 7.72 (m, 6H), 7.60-7.30 (m, 16H), 7.25 (m, 3H), 3.74 [d, 4J('H-31P) = 2.1 Hz, 3H], 2.72 [dd, J('H-'H) = 16.9 Hz, 3J('H-31P) = 1.9 Hz, 1H1, 2.44 [dd, J('H-'H) = 16.9 Hz, 3J('H-31P) = 4.8 Hz, lH]; W{'H} NMR (50 MHz, CDCl3; DEPT) 6 177.36 (C), 150.17 (C), 134.71 [d, 2J('3c-31p) = 11.7 Hz, PPh3; CHI, 133.50 (C), 130.96 [d, 1J('3C-31P) = 48.1 Hz, PPh3; C], 130.57 [d, 4J('3C-31P) = 2.5 Hz, PPh3; CHI, 130.45 (CH), 128.68 (CHI, 128.26 Id, 3J('3C-31P) = 10.7 Hz, P p b ; CHI, 128.25 (CH), 128.05 (CHI, 125.87 (CH), 121.03 (CH), 49.23 (CH3), 39.80 [d, 2J('3C-31P) = 3.9 Hz, CHz1; 31P{1H}(121.4 MHz, CDC13) 6 35.45; IR (KBr) 3035 (w), 2920 (w), 1620 (w), 1595 (w), 1575 (w), 1490 (s), 1440 (s), 1380 (w), 1270 (w), 1190 (w), 1105 (s), 1110 (m), 780 (s), 755 (s), 700 (vs), 535 (s), 510

Notes

4430 Organometallics, Vol. 14, No. 9, 1995 (s), 365 (w); HRMS m l z calcd for C ~ ~ H ~ O C ~ N 626.0870; ZPP~, found, 626.0866. Anal. Calcd for C33H30ClNzPPd: C, 63.17; H, 4.82; N, 4.46. Found C, 63.40; H, 5.10; N, 4.27. Palladacycle 16. Reaction conditions: 65 "C, 48 h. Eluent: 3:l hexane-EtOAc. Yield: 31%. 'H NMR (300 MHz, CDC13)6 7.74 (m, 6H), 7.42 (m, 9H), 3.17 [d, 4J(1H-31P)= 2.2 Hz, 3H], 3.04 [d, 4J(1H-31P) = 2.4 Hz, 3H1, 2.61 (m, lH), 2.30 (m, 2H), 1.95-1.20 (m, 4H), 0.91 (m, 2H); 13C{'H} NMR (50 MHz, CDC13; DEPT) 6 183.46 (C), 134.79 [d, 2J('3C-31P)= 11.7 Hz, PPh3; CHI, 131.12 [d, 1J(13C-31P)= 46.9 Hz, PPh3; Cl, 130.41 [d, 4J('3C-31P) = 2.0 Hz, PPh3; CHI, 128.20 [d, V(13C31P)= 10.6 Hz, PPh3; CHI, 58.20 (CH), 51.74 [d, 3J('3C-31P) = 2.0 Hz, CH31, 51.57 [d, 3J('3C-31P) = 1.7 Hz, CH31, 37.51 (CHz), 31.43 (CHz), 28.86 (CHz), 27.59 [d, 4J(13C-31P)= 5.3 Hz, CHz]; 31P{1H}(121.4 MHz, CDC13) 6 33.93; IR (KBr) 3050 (w), 2920 (m), 2860 (w), 1720 (w), 1640 (m), 1490 (m), 1340 (s), 1190 (m), 1130 (m), 1100 (s), 1000 (m), 970 (w), 940 (w), 920 (w), 755 (s), 720 (m), 705 (vs), 535 (vs), 510 (s), 360 (w); MS m l z 564 (0.21, 563 (O.l), 562 [0.3,2 (M+- PPh3) + 21,561 (0.2), 560 (0.2), 559 (O.l), 544 (0.11, 542 (0.11, 508 (0.31, 506 (0.4), 505 (0.2), 278 (37), 277 (67),262 (1001,183 (771,108 (36); HRMS m l z calcd for C&&lNaPd, 542.0870; found, 542.0866. Palladacycles 17 and 18. The palladation of 12 at 65 "C for 24 h gave a mixture of 17 and 18. Chromatography (2:l hexane-EtOAc) gave complex 17 (17%). Further elution with 1:l hexane-EtOAc and EtOAc gave 18 (54%). Palladacycle 17: 'H NMR (300 MHz, CDCl3) 6 7.72 (m, 6H), 7.43 (m, 9H), 5.68 (ddt, J = 17.9, 9.9, 6.7 Hz, lH), 4.92 (m, 2H), 3.04 [d, 4J(1H-31P)= 2.5 Hz, 6H1, 2.28 (m, 4H), 2.10 [d, 3J(1H-31P)= 3.5 Hz, 2H]; l3C{'H) NMR (50 MHz, CDC13; DEPT) 6 179.67 [d, 3J(13C-31P)= 3.7 Hz; C], 137.14 (CHI, 134.64 [d, 'J(13C31P) = 11.7 Hz, PPh3; CHI, 131.22 Id, 1J(13C-31P)= 48.8 Hz, PPh3; C], 130.51 [d, 4J('3C-31P) = 2.2 Hz, PPh3; CHI, 128.25 [d, 3J('3C-31P) = 10.5 Hz, PPh3; CHI, 115.20 (CHz), 51.49 [d, 3J('3C-3'P) = 2.0 Hz, 2 CH31, 40.38 [d,2J('3C-31P) = 4.6 Hz, CHz], 32.06 (CHz),31.32 (CHz);31P{1H}(121.4 MHz, CDC13) 6

33.55; IR (KBr) 3040 (w), 2920 (w), 1485 (m), 1435 (SI, 1105 (s), 1000 (m), 755 (SI, 700 (s), 530 (SI, 510 (SI, 360 (w); MS m l z 546 (0.6),544(l.O), 542 (1.0, M+),508 ( 0 3 , 5 0 6 ( 0 4 , 5 0 5 (0.31, 262 (1001, 183 (73); HRMS m l z calcd for CzsHaoC1NzPPd, 542.0870; found, 542.0883. Palladacycle 18: 'H NMR (200 MHz, CDC13) S 7.80-7.60 (m, 6H), 7.50-7.30 (m, 9HI, 3.17 (m, lH), 3.07 [d, 4J('H-31P) = 2.5 Hz, 3H1, 3.03 [d, *J('H31P) = 2.0 Hz, 3H], 2.24 (t, J = 7.2 Hz, 2H), 2.02 (s,3H), 1.65-

1.30(m,3H),1.14(ddd,J=9.5,6.5,3.5H~,1H);'~C{'H}NMR (50MHz, CDC13; DEPT) 6 208.33 (C), 134.64 [d, 2J('3C-31P) = 11.7 Hz, PPh3; CHI, 131.47 [d, 'J('3C-31P) = 49.0 Hz, PPh3; C], 130.33 [d, 4J('3C-31P) = 2.1 Hz, PPh3; CHI, 128.13 [d, 35('3C-3'P) = 10.6, PPh3; CHI, 61.13 (CH), 53.44 [d, 3J('3C3'P) = 2.0 Hz, CH31, 49.76 [d, 3J('3C-31P) = 1.4 Hz, CH31,41.07 [d, 2J('3C-31P)= 2.0 Hz, CHz], 40.44 (CHz),29.89 (CH3),26.97 (CH2);31P{1H}(121.4 MHz, CDC13) 6 36.10; IR (KBr) 3050 (w), 2900 (w), 1700 (m), 1480 (m), 1435 (SI, 1175 b),1110 (SI, 1090 (s), 1000 (w), 740 (m), 715 (m), 690 (s), 535 (SI, 505 (m); MS m l z 544 (