Diphenylsilane Reduction of C=O and C=N Bearing Electron-Withdrawing Group in the Presence of Aluminum(III) Chloride.

Several α-keto esters and methyl N-p-tolylsulfonyl-2-aryl-2-iminoacetates were reduced to the corresponding α-hydroxy esters and methyl N-p-tolylsulfonyl-2-arylglycinates in high yields by a combination of aluminum(III) chloride and diphenylsilane under operating conditions in which diphenylsilane was added to the pre-formed substrate-aluminum(III) chloride complex in dichloromethane and the mixture stirred. The case of an exactly equivalent amount of aluminum(III) chloride as the substrate resulted in good results.