Rhodium(I)-Catalyzed Intramolecular Carbonylative [2+2+1] Cycloaddition of Bis(allene)s: Bicyclo[6.3.0]undecadienones and Bicyclo[5.3.0]decadienones

摘要

The [Co2(CO)8]-mediated [2+2+1] cycloaddition involving an alkyne π bond, an alkene π bond, and carbon monoxide (CO) is known as the Pauson-Khand reaction, and the intramolecular Pauson-Khand reaction of enynes (alkyne/ alkene derivatives) can generally be applied to the formation of bicyclo[3.3.0]octenones and bicyclo[4.3.0]nonenones in good to high yields. However, the application of this protocol to the construction of larger systems, bicyclo[5.3.0]decenones, could not be achieved except for a few specific substrates, which have, for example, an aromatic ring as the template. The Rh~I-catalyzed carbonylative [2+2+1] cycloaddition of allenynes (alkyne/allene derivatives) or allenenes (alkene/ allene),however, has been described by us and Brum-mond et al. , to afford the corresponding bicyclo[5.3.0] compounds in satisfactory yields. Described herein are the preliminary results of the [{RhCl(CO)2}2]- and [{RhCl(CO)dppp}2]-catalyzed carbonylative ring-closing reaction of bis(allene)s to effect the preparation of the medium-sized bicyclo[m.3.0] skeletons (m = 5, 6).