Observations Made in Exploring a Pyridinium Salt Photochemical Approach to the Synthesis of (+)-Lactacystin

The key step in a strategy for the synthesis of (+)-lactacystin involving photocyclization reaction of a cyclopenta-fused pyridinium salt has been probed by using a model substrate. Observations made in this effort led to the discovery of a highly unusual cascade process that leads to stereoselective formation of an interesting tricyclic carbamate. The results of this study are presented and discussed in the context of a (+)-lactacystin synthetic approach. Key Words: (+)-Lactacystin, Cyclopenta-fused pyridinium salt, Photochemistr