Synthesis of alpha-phenylseleno-alpha,beta-unsaturated esters by Wittig-type reactions. Studies on the Diels-Alder reaction

Ethyl alpha -phenylseleno-alpha,beta -unsaturated eaters were prepared by t he reaction of tri-ethyl phosphonoacetate anion and ethoxycarbonyl(phenylse lenenyl)methylidene(triphenyl)phosphorane with aliphatic and aromatic aldeh ydes. The alpha -phenylseleno unsaturated esters were obtained as mixtures of E/Z-isomers in medium to good yields and in moderate yields, respectivel y. alpha -Phenylselenenyl acrylate was used as dienophile in a Diels-Alder reaction. On reaction with isoprene only the para isomer was obtained while reaction with cyclopentadiene gave a 1:1 mixture of exo/endo isomers in go od yield. (C) 2001 Elsevier Science B.V. All rights reserved.