Four-component Pd-catalysed cascade/ring closing metathesis. Synthesis of heterocyclic enones

摘要

A palladium-catalysed four-component process is described involving carbon monoxide, allene and aryl/heteroaryl iodides generating (pi-allyl) palladium species, which are intercepted by alkene tethered nitrogen nucleophiles to afford 1,6- and 1,7-dienones. Subsequent ring closing metathesis affords five- and six-membered N-heterocyclic enones. The N-heterocyclic enones are active dipolarophiles in 1,3-dipolar cycloaddition reactions as exemplified by azomethine ylide and nitrone cycloadditions. (c) 2005 Elsevier Ltd. All rights reserved.