Cyclic imines, ring expansion

This general strategy has also successfully been exploited for the formation of carbon-carbon bonds. Compound (38) underwent ring expansion with concomitant formation of two new carbon-carbon bonds when treated sequentially with Grignaid reagents as depicted in equation (25). Similarly, treatment of cyclic ketoxime methanesulfonates with trimethylaluminum in dichloromethane gave cyclic imines, the... 

A total synthesis of strychnofoline (277), a bisindole constituted from the union of a tetracyclic oxindole and a tryptamine unit, and previously isolated from S. usambarensis (165), has been recently reported (166). A key feature of the synthesis is the convergent assembly of the tetracyclic core containing the oxindole moiety 276 through the ring-expansion reaction of a spiro[cyclopropan-l,3-oxin-dole] 274 and a cyclic imine 275, as shown in Scheme 21. 

---