New Synthetic Method of Aldehydes from Tertiary Amides by Lithium Diisobutylpiperidinohydroaluminate (LDBPA)

Abstract

Partial reduction of tertiary amides into aldehyde is one of the most important and highly desirable means in organic synthesis, and a large number of reducing agents for this have been reported. Among them, a commercially available diisobutylaluminium hydride (DIBAH) is commonly used for the preparation of aldehydes from tertiary amides in 5070% yields. Previously, we have reported that lithium diisobutyldialkylaminohydroaluminates, the amino-derivatives of DIBAH, are new partial reducing agents, which can reduce various esters into aldehydes. Among them, lithium diisobutylpiperidinohydroaluminate (LDBPA) was most effective for partial reduction of esters to aldehydes in moderate to good yields at 0 C and also LDBPA was effective for partial reduction of aromatic nitriles in almost quantitative yield. As a part of our research program directed toward the discovery of new reducing agents through the simple modification of commercial DIBAH, we have studied the reducing characteristics of LDBPA with tertiary amides and found that LDBPA smoothly reduced tertiary amides to aldehydes at 0 C. Herein, we wish to report a new alternative and efficient method for partial reduction of tertiary amides to aldehydes by LDBPA under mild condition (Scheme 1).