Synthesis of Chiral 1,3-Dienes through Ring-Closing Metathesis of Enantioenriched Enynes: Potential Precursors of Morphane Analogs

A simple methodology for the synthesis of enynes by indium mediated diastereoselective allylation of aromatic N-tert-butanesulfinylimines bearing alkenyl groups at ortho-position with allyl bromide has been developed. The addition of the allyl indium intermediate to the chiral imine took place with excellent diastercoselectivity. Ruthenium-catalyzed ring-closing metathesis of the resulting enynes provided the expected cyclic 1,3-dienes in good to moderate yields. These chiral dienes are potential precursors of biologically and pharmacologically active morphane derivatives.