Tributyltin Hydride in NMP-Promoted Reduction of Acid Chlorides to Aldehydes under Transition-Metal-Free Conditions

Abstract

Abstract: Tributyltin hydride in N -methyl-2-pyrrolidinone (NMP)was used for the partial reduction of various functionalized acidchlorides at room temperature. This transition-metal-free procedureallows the synthesis of a range of (hetero)aromatic- and aliphatic al-dehydes in good to excellent yields. Key words: acid chlorides, aldehydes, reduction, tributyltin hy-dride, N -methyl-2-pyrrolidinone, free-metal conditions The partial reduction of acid chlorides to aldehydes seemsto be a simple reaction, yet this type of transformation re-mains a desirable tool. Over the past decades, a variety ofmethods have been developed. Besides the traditional hy-drogenolysis with Pd/BaSO 4 (Rosenmund reduction), 1 many metallic hydrides have been extensively used forsuch transformations, including, lithium or sodium tri- t -butoxyaluminium hydride, 2 sodium borohydride, 3 hyper-valent silicon hydrides, 4 transition-metal borohydrides, 5 anionic transition-metal reductants, 6 and others. 7 Howev-er, such methods have limitations, which include over-reduction, lack of generality, low yield and functionalgroup incompatibility. Alternative methods involve theuse of organosilicon