CYCLOCARBONYLATION CATALYZED BY PALLADIUM COMPLEXES

Recent reports on cyclocarbonylation reactions catalyzed by palladium complexes are briefly reviewed. These reactions provide useful synthetic routes to various types of compounds such as lactones, lactams, cyclic ketones, cyclic imides, and cyclic acid anhydrides. In the latter part of this review is described detailed account on the palladium-catalyzed cyclocarbonylation of substituted allyl compounds developed by the authors. As a typical reaction, 1-naphthyl acetate is obtained in 70-90% yield by the cyclocarbonylation of cinnamyl acetate in the presence of acetic anhydride, triethylamine, and a catalytic amount of palladium complex such as PdCl2-(PPh3)2 under 50-70 atm of carbon monoxide at 160-degrees-C. Acetoxy-substituted phenanthrenes, benzofurans, benzothiophenes, indoles, and carbazoles are also obtained in good yields by the similar reactions of 3-(aryl)allyl acetates. On the other hand, the cyclocarbonylation of 2,4-pentadienyl acetates selectively give phenyl acetates.