A New Modular Indole Synthesis. Construction of the Highly Strained CDEF Parent Tetracycle of Nodulisporic Acids A and B

Construction of the highly strained CDEF parent tetracycle, a structural motif found only in the potent ectoparasiticidal agents (+)-nodulisporic acids A and B and related congeners, has been achieved via a new modular indole synthesis, exploiting a sequential Stille cross-coupling/Buchwald−Hartwig union/cyclization tactic. The new indole synthesis holds the promise of rapid assembly of diverse, highly substituted indoles possessing uncommon substitution patterns.