Synthesis of Caprolactams from Cyclic Imines by Cross-Metathesis

Abstract

Reported is the synthesis of α,β-unsaturated-δ-oxacaprolactams from heterocyclic imines using an interesting alkene metathesis. The starting heterocyclic acrylamides were formed in poor to good yield through the reaction of imines with acid chlorides, followed by quenching the resulting α-chloroamines with allyl alcohol. The me­tathesis reactions proceed in moderate to very good yields using the Grubbs II catalyst. The less expensive Grubbs I catalyst was tested but gave lower yields of products.