[3 + 2] CYCLOADDITIONS OF AZOMETHINEIMINES

摘要

The history of azomethine imines in contrast to the majority of stable 1,3-dipoles, which have been known for more than a century, began only relatively recently. The first stable azomethine imine, a sydnone, was reported by Earl and McKaney in 1935, but its 1,3-dipolar character was not recognized until the 1960s. Huisgen and co-workers immediately recognized the utility of the 1,3-dipolar functionality of 1-(4-chlorophenyl)-2-cyano-1-(9H-fluoren-9-ylidene)hydrazin-1-ium-2-ide in a series of [3 + 2] cycloadditions with alkenes, acetylenes, and cumulenes. The preparation and chemistry of azomethine imines until 2004 has been reviewed by Grashey and Schantl. Since the beginning of the 21~(st) century, the interest in [3 + 2] cycloadditions of azomethine imines has risen significantly, particularly in the area of catalyzed and asymmetric cycloadditions. The 1,3-dipolar cycloadditions of azomethine imines since 2003 have been reviewed by Najera and co-workers.