A Photochemical Route for Erythrane Ring Construction

Article abstract of DOI:10.1021/jo00384a018

A novel strategy for synthesis of members of the erythrina alkaloid family is described.The route features an electron-transfer-induced, photocyclization process which is used to construct the spirocyclic tricyclic framework of these substances.The tricyclic intermediate 15, generated (60percent) by irradiation of the corresponding (silylalkenyl)-3,4-dihydroisoquinolinium perchlorate 14, is transformed to the tetracyclic dione 17 or ketone 26 by use of respective Claisen and alkylation-cyclization processes.The methodology is demonstrated by its application to the synthesis of the known 15,16-dimethoxy-cis-erythrinan 27.