Conolutinine, a hexacyclic indole alkaloid with a novel ring system incorporating a diazaspiro center and fused oxadiazepine–tetrahydrofuran rings

A hexacyclic indole alkaloid possessing an unprecedented ring system incorporating a diazaspiro center and fused oxadiazepine–tetrahydrofuran rings has been isolated from the Malayan Tabernaemontana corymbosa. The structure was established by analysis of the spectroscopic data and a possible biogenetic pathway from a cleavamine-type precursor is presented.