Jp. Konopelski et Ra. Kasar, SYNTHESIS AND REACTIONS OF ACHIRAL 3-SUBSTITUTED VINYLKETENE ACETALS AS DIENES IN THE DIELS-ALDER REACTION, Tetrahedron letters, 34(29), 1993, pp. 4587-4590
The synthesis of three new vinylketene acetals, each bearing a heteroa
tom substituent at C3 of the diene unit, and their reactions with repr
esentative dienophiles in Diels-Alder reactions are presented. All the
dienes react well at room temperature, indicating substantial activat
ion of the cycloaddition event. The stereochemistry of the major Diels
-Alder product of a 3-SPh-substituted vinylketene acetal is opposite t
o that produced by the corresponding 3-unsubstituted compound.