Development of an Intramolecular Aryne Ene Reaction and Application to the Formal Synthesis of (±)-Crinine

A general and high yielding annulation strategy for the synthesis of various carbo- and heterocycles, based on an intramolecular aryne ene reaction is described. It was found that the geometry of the olefin is crucial to the success of the reaction, with exclusive migration of the <i>trans</i>-allylic-H taking place. Furthermore, the electronic nature of the aryne was found to be important to the success of the reaction. Deuterium labeling studies and DFT calculations provided insight into the reaction mechanism. The data suggests a concerted asynchronous transition state, resembling a nucleophilic attack on the aryne. This strategy was successfully applied to the formal synthesis of the ethanophenanthridine alkaloid (±)-crinine

Synthesis of Multisubstituted Pyridines

By utilizing amino allenes, aldehydes, and aryl iodides as readily available building blocks, a simple and modular synthesis of multisubstituted pyridines with flexible control over the substitution pattern has been achieved. The method employs a two-step procedure involving the preparation of “skipped” allenyl imines and a subsequent palladium-catalyzed cyclization