Silyl substituted furans in the stereoselective Birch reduction

Chiral derivatives of 3-silyl-2-furoic acid were prepared and subjected to a Birch reductive alkylation reaction. It was found that the presence of a silicon atom, ortho to the chiral auxiliary, enabled the synthesis of dihydrofurans with high levels of stereoselectivity. We believe that the silicon group is essential in order to control the geometry of the enolate formed in the reduction regime. Remarkably, the partial reduction conditions could be tailored so that the silicon is removed in situ, before the furan derived enolate is alkylated.