D. A. Evans. D M. Barnes Allyl and Crotyl Metal Species-4: Catalytic Systems a Three Catalytic Asymmetric Allylations of Aldehydes are Known Ti(OiPr)4, 4A sieves COOH +BH3THF— 20 mol % BLn HcHO Ti(OiPr 4A EZ 63% yield CF3COOH or TfOH 90% H. Yamamoto, Synlett 1991, 561-562. 102(10m%)RCHo Yield (% 88 20 mol 42 n-C7H15CHO G. Keck J. Am. chem. Soc. 1993. 115. 8467-8468 ETagliavini,A. Umani-Ronchi J. Am. Chem. Soc. 1993, 115, 7001-7002. i Many Other Metals Have Been Employed in the Allylation Reaction Pb: S. Toni. Chem. Lett. 1986. 1461-1462 Mo: J Faller. Tetrahedron Lett. 1991. 32. 1271-1274 Cr: Y Kishi. Tetrahedron Lett. 1982. 23. 2343-2346 b: Y. Butsugan, Tetrahedron ron lett1987,28,3707-3708 Mn: T. Hiyama, OrganometalliCS, 1982, 1, 1249-1251 Zn: T Shono. Chem. Lett. 1990. 449-452 Ba: H. Yamamoto. J. Am. Chem. Soc. 1991. 113. 8955-8956 19A-04a-Allyl/Crotyl 4 1/19/00 1: 49 PMPb: S. Torii, Chem. Lett. 1986, 1461-1462. Mo: J. Faller, Tetrahedron Lett. 1991, 32, 1271-1274. Cr: Y. Kishi, Tetrahedron Lett. 1982, 23, 2343-2346. P. Knochel, J. Org. Chem. 1992, 57, 6384-6386. Sb: Y. Butsugan, Tetrahedron Lett. 1987, 28, 3707-3708. Mn: T. Hiyama, Organometallics, 1982, 1, 1249-1251. Zn: T. Shono, Chem. Lett. 1990, 449-452. Ba: H. Yamamoto, J. Am. Chem. Soc. 1991, 113, 8955-8956. ■ Many Other Metals Have Been Employed in the Allylation Reaction ... D. A. Evans, D. M. Barnes Allyl and Crotyl Metal Species-4: Catalytic Systems Chem 115 ■ Three Catalytic Asymmetric Allylations of Aldehydes are Known + BH3-THF BLn* E/Z = 61/39 + PhCHO 20 mol % BLn* H. Yamamoto, Synlett 1991, 561-562. n-C7H15CHO + 81% yield 97.4% ee 63% yield 90% ee E. Tagliavini, A. Umani-Ronchi J. Am. Chem. Soc. 1993, 115, 7001-7002. G. Keck J. Am. Chem. Soc. 1993, 115, 8467-8468. 20 mol % Ti(OiPr)4, 4Â sieves Ti(OiPr)4, 4Â sieves CF3COOH or TfOH 1 2 1 or 2 (10 mol %), RCHO R Ph Chex Catalyst 1 2 1 2 1 2 Yield (%) 88 98 66 95 42 78 ee (%) 95 92 94 92 89 77 COOH iPrO OiPr O OH COOH Me SiMe3 Me Ph Me OH Me O O Ti Cl Cl SnBu3 n-C7H15 OH H O SnBu3 R OH OH OH O O Ti OiPr OiPr OH OH O O Ti O O 19A-04a - Allyl/Crotyl 4 1/19/00 1:49 PM