New carbon-carbon bond formation through oxyallylation of enoxysilanes with sulfur dioxide adduct of 1-methoxybutadiene. Stereoselective synthesis of (Z)-4-methoxy-6-oxoalk-2-enyl methyl sulfones

Article abstract of DOI:10.1016/S0040-4039(97)01397-X

Mixtures of 1-methoxybutadiene, trimethylsilyl enol ethers, SO₂ and a Lewis acid catalyst generate trimethylsilyl (Z)-4-methoxy-6-oxoalk-2-enesulfinates that can be converted into 4-methoxy-6-oxoalk-2-enyl methyl sulfones and 5-alkyl-4-methoxy-6-oxoalk-2-enyl methyl sulfones with 100% (Z) selectivity and good syn diastereoselectivity for the 5-alkyl and 4-methoxy substituents.