Asymmetric rhodium-catalyzed intramolecular hydroacylation for fivemembered ring ketone formation

The rhodium-catalyzed intramolecular hydroacylation of unsaturated aldehydes leads to the formation of cyclopentanone derivatives. The cyclization catalyzed by Wilkinson's complex is highly diastereoselective, and via this reaction, 3,4-disubstituted 4-pentenals were used to prepare the four stereoisomers of 3,4-disubstituted cyclopentanones. Several biologically active molecules, including 8-isoprostanoic acid, prostanoic acid, (-)-brefeldin A, 11-deoxyprostaglandin, and the nepetalactones, have been synthesized in enantiomerically pure form from these cyclopentanones. In this review, the asymmetric synthesis of cyclopentanones via the enantioselective cyclization catalyzed by rhodium complex incorporating optically active ligands will be discussed.