Dearomative reduction of arenes through the use of arenophiles & studies towards the synthesis of cardiotonic steroids calotropin and calactin

[摘要] A novel method for the dearomative reduction of arenes through the use of N,N-arenophile, MTAD, was developed. Cheap feedstock arenes undergo photocycloaddition with MTAD, and the cycloadduct can be treated further to furnish novel 1,3-cyclohexadienes or 1,4-diamino-2- cyclohexenes. The utility of this method is shown in the synthesis of a natural product in two steps from naphthalene.Calotropin, a cardiotonic steroid, isolated from Apocynaceae plants is a highly cytotoxic natural product with anti-cancer activity. A total synthesis strategy which utilizes a NHC-catalyzed benzoin condensation, and Pd-catalyzed nucleophilic dearomatization of a phenol is described. Also described, is the semisynthetic strategy towards calotropin from estrone, where the aromatic A ring is dearomatized to introduce a C1 fragment at the para-position.

[效力级别] Total synthesis

[关键词] Organic chemistry;Total synthesis;Methodology;Dearomative functionalization