Efforts Toward a Unified Kainoid Family Synthesis Approach: Unexpected Sulfinamide-Directed Conjugate Addition Results

A short asymmetric synthesis of an all-syn and all-trans kainoid core is reported. The synthetic route relies on the application of a new asymmetric [3+2] annulation reaction followed by a conjugate addition reaction to install this kainoid's three stereocenters. A surprising intramolecular conjugate addition enabled by the chiral tert-butylsulfinyl group residing on the 3-pyrroline nitrogen atom surpassed its expected role as a steric spectator. Efforts to outcompete intramolecular 1,4-addition by further oxidizing the sulfoxide, or use of additives, and advancement of the all-syn addition product to the requisite kainoid common core are detailed.