摘要

A novel total synthesis of laurencenone C, a chamigrene sesquitepenoid natural product, has been accomplished in 11 steps. In the synthetic sequence, the B-ring of the spirocyclic core was constructed by a one-pot operation involving a Knoevenagel condensation between ethyl cyanoacetate and paraformaldehyde combined with a Diels-Alder reaction of the resulting ethyl 2-cyanoacrylate with isoprene. Moreover, a lithium naphthalenide-induced reductive alkylation of the Diels-Alder adduct was employed to create the C-6 quaternary center and to set the stage for assembling the A-ring.