Organometallics 1995, 14, 5450-5453
5450
Ligand-Dependent Relative Stability Order in Allyl SulfidePalladium(0) Species us (q3-Allyl)palladium(II) Thiolate Species Yoshinori Miyauchi, Saisuke Watanabe, Hitoshi Kuniyasu, and Hideo Kurosawa* Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565, Japan Received July 13, 1995@ Summary: Oxidative additions of allyl phenyl sulfide and selenide to Pdz(dba)s or Pd(MA)(COD) (dba = dibenzylideneacetone, M A = maleic anhydride, COD = cyclooctadiene)provided [Pd($-C&,YEPh)]~(E = S, Se) in good yields. Competitive reactions employing the sulfide and the selenide showed the higher reactivity of the selenide with regard to oxidative addition. The reaction of [Pd(q3-Cfld(SPh)1zwith PR3 afforded different types of products, depending on the nature of R and the molar ratio of the reagents. The reaction with both 1 equiv and 2 equiv of PCy3 (Cy = cyclohexyl) gave Pdl$-Cfld(SPh)(PCyd as the sole product. In the reactions with PPh3 and P(OMe)3, comparable amounts of the p-allyl Pd-Pd complex Pddp-Cfld(p-SPh)(PRdz (R = Ph, OMe) and allyl phenyl sulfide were obtained in the case of PR3lPd = 1, while the latter product predominated in the case of PR3lPd > 3. Analogous reactions employing q3-5-(methoxycarbonyl)cyclohexenyl analogs and excess PPh3 indicated that the formation of allyl phenyl sulfides took place with inversion of stereochemistry at the allylic carbon, suggesting ex0 attack of the thiolate at the $-allyl group in [Pd($-allyl)(PPh&Ji. Introduction Cleavage and formation of C-S bonds mediated by transition metal complexes are subjects of increasing synthetic and mechanistic interest.l Allylic sulfides and selenides reacted with Pd(0)-trialkylphosphine complexes to give dinuclear p-allylic complexes probably via oxidative addition to generate allylpalladium(I1)thiolate and selenolate intermediates, followed by their reaction with the Pd(0) complex? but definitive evidence for this Abstract published in Advance ACS Abstracts, November 1,1995. (1)(a) Petillon, F. Y.; Le Floch-Perennou, F.; Guerchais, J. E.; Sharp, D. W. A. J . Organomet. Chem. 1979,173,89.(b) Osakada, K.; Maeda, M.; Nakamura, Y.; Yamamoto, T.; Yamamoto, A. J. Chem. SOC.,Chem. Ogawa, A.; Miyazaki, S.; Ryu, Commun. 1986,442.( c ) Kuniyasu, H.; I.; Kambe, N.; Sonoda, N. J. Am. Chem. SOC.1991, 113, 9796. (d) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Kambe, N.; Sonoda, N. J. Am. Chem. Soc. 1992,114,5902. ( e )Nishio, M.; Matsuzaka, H.; Mizobe, Y.; Hidai, M. J. Chem. Sac., Chem. Commun. 1993,375.(0 Garcia, J. J.; Maitlis, P. M. J . Am. Chem. Soc. 1993,115,12200.(g) Wong, K.; Yuan, T.; Wang, M. C.; Tung, H.; Luh, T. J. Am. Chem. Soc. 1994, 116,8920.(h) Jones, W. D.; Chin, R. M. J . Am. Chem. Soc. 1994,116, 198.(i) Rondon, D.;Delbeau, J.; He, X.; Sabo-Etienne, S.; Chaudret, (i) Martinez, A. G.; Barcina, B. J . Chem.Soc., Dalton Trans. 1994,1895. J. 0.;Cerezo, A. F.; Subramanian, L. R. Synlett. 1994,561.(k) Garcia, J. J.; Mann, B. E.; Adams, H.; Bailey, N. A,; Maitlis, P. M. J. Am. Chem. SOC.1995,117,2179.(1) Baranano, D.; Hartwig, J . F. J. Am. Chem. Sac. 1995,11 7,2937. (2)(a)Yamamoto, T.; Akimoto, M.; Saito, 0.;Yamamoto, A. Orgunometallics 1986,5,1559. (b) Osakada, K.;Chiba, T.; Nakamura, Y.; Yamamoto, T.; Yamamoto, A. Organometallics 1989, 8, 2602. ( c ) Osakada, K.; Ozawa, Y.; Yamamoto, A. J. Organomet. Chem. 19S0, 399, 341. @
sequence was lacking. In contrast, it has been proposed in some catalytic transformations of allylic substrates3 that similar (q3-allyl)palladium(II)thiolate intermediates are rather prone to undergo reductive elimination to generate allylic sulfides and Pd(0) species. In order to shed more light on such apparently conflicting stability order of a Pd(0) complex plus allyl sulfide on one side and an allylpalladium(I1) thiolate complex on the other (Scheme 11, we examined reactions of related (y3-allyl)palladium(II)thiolate and selenolate complexes with some ligands. Reported herein are results of such experiments and a unified explanation for the previous findings. Scheme 1
Results and Discussion When the reaction of allyl phenyl sulfide (1) and Pd,(dba)3 was carried out in CDC13 solution a t ambient temperature for 3 h, the formation of (q3-allyl)palladium benzenethiolate, [Pd(q3-C3Hd(SPh)12(2),4 in 78% yield was confirmed by the lH NMR spectrum (eq 1). A
1 Y = S 3 Y = Se
2 Y = S 4 Y = Se
similar treatment using allyl phenyl selenide 3 gave the corresponding selenolate complex 44 in 88%yield. The oxidative addition also occurred in the reaction between Pd(MA)(COD)and 1 or 3. When a 1:l mixture of 1 and 3 was reacted with Pdddbah, formation of 4 predominated over that of 2, suggesting much higher reactivity of the selenide. This trend is different from that in the corresponding reaction of Pd(PCy3)z with 1 and 3,where the two substrates showed similar reactivities.2a The facile oxidative addition of 1 and 3 to Pd(0)-olefin complexes can be compared with the known reactivity patterns between 1 and Pd(O)-PR3 complexes;2a no reaction took place in the case of R = Ph, but apparent oxidative addition occurred in the case of R = Cy. Attempts were made t o rationalize these results by examining reactions of 2 and 4 with various PR3 species. (3)(a) Auburn. P. R.: Whelan. J.:Bosnich. B. J. Chem. SOC..Chem. Commun. 1986,146.(b) Goux, C.;Lhoste, P.; Sinou, D. Tetrahedron 1994,50,10321.
0276-7333/95/2314-5450$09.QQ~O 1995 American Chemical Society
Organometallics, Vol. 14, No. 11, 1995 5451
Notes
Chart 1
The reaction of 2 with 1 equiv of PCy3 in CHzCl2 or
CDC13 at room temperature gave Pd(q3-C3H5)(SPh)(PCy3) (5) in 61% yield (eq 2). Addition of another 1 2
+
PCy3
e
f.t.,
CDC13
*
+d
