Exploratory Studies of α-Silylamino and α-Silylamido 2,5-Cyclohexadien-1-one SET Photochemistry. Methodology for Synthesis of Functionalized Hydroisoquinolines

Article abstract of DOI:10.1021/jo00048a046

The electron-transfer (SET) photochemistry of selected α-silylamino and α-silylamido 2,5-cyclohexadienones has been explored with the intent of developing a novel and potentially efficient method for functionalized hydroisoquinoline synthesis.These substances, prepared by Birch reduction-alkylation-oxidation sequences, were found to undergo 9,10-dicyanoanthracene-SET-sensitized radical cyclization to form hydroisoquinolines in a highly regio- and stereoselective fashion and in modest to good yields.In contrast, the major direct irradiation reaction pathway followed by the α-silylamido-substituted systems involves type A rearrangement to bicyclic cyclohexenones or phenols.Direct irradiation of the α-silylamino analogs, on the other hand, brings about near-exclusive conversion to the corresponding hydroisoquinolines.The synthetic and mechanistic features of this study are described.