Total synthesis of the biscarbazole alkaloids murrafoline A-D by a domino sonogashira coupling/claisen rearrangement/electrocyclization reaction

Abstract

Why take things one step at a time? Aryl-pyran-linked biscarbazole alkaloids of the murrafoline group (see crystal structure of murrafoline A; dark gray: C, red: O, blue: N) were accessed readily by a novel domino reaction sequence involving Sonogashira coupling, a Claisen rearrangement, and electrocyclization. The one-pot procedure enables the straightforward synthesis of these structurally challenging alkaloids in only a few steps.

Keywords: CH bond activation; X-ray diffraction; alkaloids; natural products; palladium.