A Flexible Metal-catalyzed Synthesis of Highly Substituted Aryl Phenanthrenyl selenides

Abstract

An efficient method for the preparation of diaryl selenides, which are important in biology and materials science, is described. Specifically, the development of highly substituted phenanthrenyl phenyl selenides 4 and 6 by metal-catalyzed cyclization of o-phenylarylalkynes species 1 was successfully performed. The selectivity for 9- and 10-selenyl phenanthrenes was perfectly controlled by indium(III) and gold(I) catalysts, and the reactions proceed through different path-ways. For the In(OTf)(3) catalyst system, 6-endo cyclization of alkyne 3 gives product 4 in which the selenium group is retained. In contrast, for the AuCl(IPr)/AgSbF6 catalyst system, transformation of metal-alkyne complex 2 into vinylidene-gold intermediate 5 gives product 6 in which the selenium group is migrated. Various substrates, even electronically poor substrates, can be converted into phenanthrenes with high selectivity in high yield under very mild conditions.