A Novel Route to the Fused Maleic Anhydride Moiety of CP Molecules.

A seven-step cascade reaction-in which selective mesylation, epoxide formation, epoxide lysis, cyclization, reiterative oxidation, and nitrogen-oxygen exchange occur sequentially-facilitates the construction of the maleic anhydride moiety of CP molecules 1 and 2 (>93% yield per step). Unstable intermediates of this reaction sequence were detected, providing evidence for the proposed mechanism and resulting in the discovery of a new chemical entity.