The potassium dienolate of prenal obtained by treatment of the corresponding dienoxysilane with tBuOK was reacted with enaldehydes. In all cases a gamma-specific reaction occurs. According to the reaction conditions gamma;1,2 or a gamma;1,4 coupled product was selectively obtained with enals. The gamma;1,2 reaction provided an efficient prenylation procedure. A short two-step synthesis of retinal is described. (C) 1998 Elsevier Science Ltd. All rights reserved.