Diastereoselective 1,3-dipolar cycloaddition of pyrylium ylides with chiral enamides

Abstract

Chiral enamides 5f-i were found to react with pyrylium ylides to give cycloadducts 6d-i in good yields with an excellent level of stereoselectivity. The chiral auxiliary was successfully removed on hydrogenolysis of compound 6f in continuous flow (H-Cube) resulting in the first asymmetric synthesis of complex amine 8. © 2012 The Royal Society of Chemistry.