Preliminary study of the total synthesis of Bao Gong Teng A analogs using 8-benzyl-2-oxo-8-azabicyclo[3.2.1]-oct-3-ene-6-endo/exo- and 7-endo/exo-carbonitrile

The use of four cycloadducts from the Katritzky reaction for subsequent pre paration of Bao Gong Teng A analogs was studied. We show that the reduction of 2-oxo-8-azabicyclo[3.2.1]octanes (1-4) to alcohols allows the 2 exo/end o isomerism to be exploited. The 7-endo compound (4) also yielded azatricyc lo[5.2.1.0(4.8)]decanone (12) from alcohol (11). When the nitrile was conve rted into an acetyl group, 6-endo products (13) and (14) were isomerized to 6-exo. Trimethylsilyloxy derivatives (13-18) ultimately yielded 2-hydroxya znbicyclooctethanone (22-24). These results afford an approach to the synth esis of the 6-exo 2-endo, 7-exo 2-exo and 7-exo 2-endo isomers of Bao Gong Teng A.