Silyl Enol Ethers as Protective Groups for Alkyl 4-Halo-3-oxobutanoates in the Arbuzov Reaction with Triethyl Phosphite

Alkyl 4-bromo- and 4-chloro-3-oxobutanoates were protected as silyl enol ethers. The Arbnzov reaction of these new compounds with triethyl phosphite gave the corresponding silyl enol phosphonates in high yield. Facile deprotection of the silyl group with water gave alkyl 4-(diethoxyphosphinyl)-3-oxobutanoates in high yields. Protection of 1-methylethyl 4-bromo-3-oxobutanoate as the enol acetate followed by the subsequent reaction with triethyl phosphite gave the corresponding phosphonate in high yield. Deprotection with potassium 2-propoxide gave 1-methylethyl 4-(diethoxyphosphinyl)-3-oxobutanoate in good yield. ©1997 John Wiley & Sons, Inc.