2-[[(p-Nitrophenyl)sulfonyl]oxy] 3-Keto Esters as Intermediates for the Regiospecific Preparation of 2-[[(p-Nitrophenyl)sulfonyl]oxy] Ketones
作者:Robert V. Hoffman、Hwa-Ok Kim、Jong Chan Lee
DOI:10.1021/jo00086a060
日期:1994.4
Stereoselective reduction of 2-methyl-3-oxo esters (or amides) with sodium borohydride catalyzed by manganese(II) chloride or tetrabutylammonium borohydride. A practical preparation of erythro and threo-3-hydroxy-2-methyl esters (or amides)
lpropionamides were prepared with high stereoselectivity by NaBH4reduction of the corresponding 2-methyl-3-oxo esters or 2-methyl-3-oxo amides in the presence of a catalytic amount of manganese(II) chloride. On the other hand, reduction of these substrates with n-Bu4NBH4 provided threo-isomers selectively. erythro-Selective reduction of 2-methyl-3-oxo amides with NaBH3CN in 1N HCl-MeOH is also described