Optically pure (S)-cyclopent-2-en-1-ol, [Formula: see text] (c 1.1, CHCl3), and (S)-3-methoxycyclopentene, [Formula: see text] (c 3.86, n-hexane), were prepared from ethyl (1R,2S)-2-hydroxycyclopentanecarboxylate, which is readily available by yeast reduction of ethyl 2-oxocyclopentanecarboxylate. The optical purity of the alcohol was determined from its Mosher ester, and that of the ether by gas chromatography using a Ni-4-Pin column. Keywords: (S)-cyclopent-2-en-1-ol, (S)-3-methoxycyclopentene.