Diastereoselective Addition of Prochiral Nucleophilic Alkenes to α-Chiral N -Sulfonyl Imines.

The Lewis-acid-promoted addition of prochiral E - and Z -allyl nucleophiles to chiral α-alkoxy N -tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C1, C2, and C3 of the resulting 2-alkoxy-3- N -tosyl-4-alkyl-5-hexene products. A computational analysis to elucidate the high selectivity is also presented. This methodology was employed in the synthesis of two naturally occurring isomers of clausenamide.