Addition Reactions of (Phenylsulfonyl)propadiene with 1-Pyrrolidinyl Enamines of Cyclic Ketones: Syntheses and Reactions of 1,3-Dienes Possessing an Allyl Sulfone Moiety

Article abstract of DOI:10.1021/jo00376a009

Addition reactions of (phenylsulfonyl)propadiene (1) with various 1-pyrrolidinyl enamines have been investigated.Allene 1 and enamines of cyclic ketones (2, 7-14) readily underwent the Michael-type addition reactions at -50 deg C to give the adducts 3, 15-20, and/or their isomers 4 and 21-26, which apparently arose by base-catalyzed isomerization of the former.These adducts were conveniently converted into the corresponding 1,3-dienes possessing allyl sulfone moiety (28, 38-45) through allyl acetates (27, 30-37) by base-promoted (n-BuLi, -50 deg C) 1,4-elimination of acetic acid to vinyl sulfones followed by deconjugation to allyl sulfones.The synthetic versatility of these dienes was revealed by the Diels-Alder reactions with dimethyl acetylenedicarboxylate (DMAD) and alkylation reactions via α-sulfonyl carbanions.