Reducing Characteristics of Metal Diisobutyl-t-butoxyaluminum Hydrides for Tertiary Amides

Abstract

A simple and useful partial reduction of tertiary amides into aldehydes is one of the highly desirable means in organic synthesis, and hence some useful reducing agents for this have been reported.1 Recently, we have reported that a new class of reducing agents, metal diisobutyl-t-butoxyaluminum hydrides such as lithium diisobutyl-t-butoxyaluminum hydride (LDBBA),2a sodium diisobutyl-t-butoxyaluminum hydride (SDBBA),2b and potassium diisobutyl-tbutoxyaluminum hydride (PDBBA),2c are new effective partial reducing agents which can reduce various esters to aldehydes in high yields. Among them, LDBBA was especially effective for partial reduction of isopropyl esters to aldehydes usually in higher than 90% at 0 oC. Also, SDBBA and PDBBA were effective for partial reduction of common methyl and ethyl esters in high yield (71-93%) at 0 oC.