Synthesis of cantharidin

Abstract

The invention provides synthetic methods for the preparation of cantharidin and analogs thereof. In one aspect, the invention provides an improved Diels-Alder cycloaddition to generate a key intermediate en route to cantharidin and analogs thereof. In certain embodiments, the new Diels-Alder reaction involves reacting Compound (2) in the presence of furan, and in the absence of acid or increased pressure, in an aprotic polar solvent with slight warming, to yield Compound (1) in favorable yield and exo-endo ratio. In another aspect, the invention also provides a new Diels-Alder reaction between compounds of Formula (III) and furan to yield compounds of Formula (IV), which can then be transformed into cantharidin or analogs thereof. In yet another aspect, the invention describes a new palladium-mediated carbonylation providing another key intermediate en route to cantharidin and analogs thereof. In addition to synthetic methods, present invention also provides compounds (i.e., intermediates) useful in the synthesis of cantharidin and analogs thereof. Compounds provided herein may have biological activity, and therefore may be used in the treatment of diseases or conditions (e.g., infectious diseases and skin conditions).