Reduction of a-Pyrone Derivatives with Borane-Methyl Sulfide Complex

Abstract

Selective reduction of the 5-carbomethoxy- and the 5-carbethoxy-4-hydroxy-2H-pyran-2-one derivatives (5a∼11, 19) to yield the 5-hydroxymethyl derivatives (12∼18) was accomplished using 1.1 mol equivalent of borane-methyl sulfide complex. Additionally, reduction of the 3-acetyl-4-hydroxy-2H-pyran-2-one derivatives (23, 26 and 29) with borane-methyl sulfide complex afforded the binary condensed pyrone derivatives (25, 28 and 31) in good yields