REDUCTION OF ALPHA-PYRONE DERIVATIVES WITH BORANE-METHYL SULFIDE COMPLEX

Selective reduction of the 5-carbomethoxy- and the 5-carbethoxy-4-hydroxy-2H-pyran-2-one derivatives (5a approximately 11, 19) to yield the 5-hydroxymethyl derivatives (12 approximately 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 3 1) in good yields.