Bakers' Yeast Reductions of Alkyl Levulinates: Synthesis of (R)-(+) and (S)-(-)4-methylbutyrolactones

The bakers' yeast reduction of a number of alkyl levulinates occurs in good to moderate yields to give the corresponding (S) alcohols in > 98% ee. The (S) alcohol la has been converted to synthetically useful (S)- or (R)-4- methylbutyro-lactone and (S)-(+)-l,4-pentanediol in good yields.