Acetalization of 5-hydroxyfuran-2 [5 H]-one with l-menthol yields (5 R)-(1) and (5 S)-5-l- menthyloxyfuran-2 [5 H]-one (2) in equal amounts. The diastereomer 1 crystallizes preferentially. For the first time, the isolation of pure diastereoisomer 2 is reported. Different