Double Annulative Cascade of Tryptophan-Containing Peptides Triggered by Selectfluor

A common dearomative strategy toward the kapakahines B/F and chaetominine natural products is reported. The proposed biomimetic strategy generates the tetracyclic α-carboline core in a single step, featuring a selectfluor-mediated dearomatization of preactivated N-Phth-Trp-Xaa-OR dipeptides at the C-terminus. The pivotal cascade includes a double annulation and the formation of three carbon–heteroatom bonds while gaining, for the first time, some insight on the diastereoselectivity outcome during the formation of the α-carboline fragment.