Palladium-catalyzed conversion of beta,gamma-unsaturated silyl sulfinates into (E)-alkenes: asymmetric synthesis of polypropionate fragments.
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)/PPh(3) 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.
Huang
Xiaogen
X
Laboratory of Glycochemistry and Asymmetric Synthesis, Swiss Federal Institute of Technology, EPFL-BCH, CH-1015 Lausanne-Dorigny, Switzerland.
Craita
Cotinica
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Vogel
Pierre
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