At low temperature, 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or protic acid generating zwitterionic intermediates that can be quenched by enoxysilanes. The resulting beta,gamma-unsaturated silyl sulfinates can be desilylated by 1:1 Pd(OAc)(2)/PPh3 catalyst, liberating the corresponding beta,gamma-unsaturated sulfinic acids that undergo smooth and highly stereoselective retro-ene eliminations of sulfur dioxide. The method has been applied to generate enantiomerically pure polypropionate fragments.
Andrea Baccarini, Imad El Haddad, Mihnea Surdu, Lubna Dada, André Welti, Houssni Lamkaddam
Athanasios Nenes, Satoshi Takahama, Spyros Pandis, Mária Lbadaoui-Darvas
Julia Schmale, Andrea Baccarini