Ruthenium catalyzed one-pot synthesis of dihydro-pyrrol-2-one derivatives from α,β-unsaturated imines, carbon monoxide and ethylene

The use of Ru-3(CO)(12) as a precatalyst induces a catalytic C-C coupling reaction of alpha,beta-unsaturated imines with CO to yield imines with an aldehyde function in beta-position with respect to the C-N double bond. An intramolecular cyclization reaction takes place via the nucleophilic attack of the imine nitrogen towards the carbonyl carbon atom building up a pyrrol-2-one system. A second ruthenium catalyzed C-C coupling reaction leads to the formal insertion of one molecule of ethylene into a C-H bond of the pyrrol-2-one in ortho position with respect to the keto group. By this selective reaction cascade imines derived from cinnamaldehyde or crotonic aldehyde, respectively, produce 1,3-dihydro-pyrrol-2-one derivatives. The analogous reaction starting from beta-naphthylaldimines yields 9b-ethyl-4-propionyl-2,9b-dihydro-benzo[e]isoindol- 1-one derivatives as a new class of heterocyclic compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.