The SmI2-mediated reductive coupling between alkynyloxiranes and ketones provides a new route to 2,3-pentadiene-1,5-diols. The preferred stereochemistry observed in the coupling products is the result of the new C-C bond forming anti with respect to the opening epoxide ring. Yields and diastereoselectivities are dependent on the alkynyloxirane substitution pattern. (C) 1998 Elsevier Science Ltd. All rights reserved.