STEREOCONTROL IN THE INTRAMOLECULAR NITRONE CYCLOADDITION TO VINYL SULFUR DERIVATIVES

The intramolecular cycloaddition to vinyl sulphur derivatives of a series of nitrones featuring an alkyl or alkoxy substituted α-stereocenter on the tether connecting dipole and dipolarophile occurs in a completely stereoselective fashion to give 3′,3-anti configurated products. The synthetic potentialities of this reaction is illustrated by the synthesis of a precursor of (d)-biotin.