文档介绍：4630 J. Am. Chem. SOC. 1984, 106, 4630-4632 Table 11. TFA-Catalyzed Erythro-Selective Ketone Reduction with PhMeSH" product threo: run ketone time, h (7% yield)b erythroC - I <1:99 (87) Ph 1 I 2 We 3 4 Typically 1 .l- mmol of PhMe2SiH and 1 mmol of a ketone were allowed to react in 1-2 mL of TFA at 0 bThe benzoyl protecting group was removed under basic (1 M KOH/MeOH, .) condition, and the total yield is given. The isolated major product is illustrated. 'Determined by 'H NMR analysis. The amino alcohol 2 gave a peak at 6 (d, J = 3 Hz, CH-OH) and 4 at 6 (d, J = 4 Hz). dThis amino alcohol gave a peak at 6 (d, J = 3 Hz, CH-OH). [R3SiHF]-[n-Bu4N]+ species which attacks the ketone carbonyl carbon according to the Felkin transition-state Par- ticularly noteworthy is that no metal cations are involved in the reaction. Thus, coordination effects by a metal cation are com- pletely eliminated, and only the bulkiness of the reagent accounts for the stereoselectivity. In this sense, the reagent is characterized as a "bulky naked hydride".13 In striking contrast to the TBAF-catalyzed threo-directed re- duction, erythro-selective reduction was achieved by using the same hydro