Four-Step Total Synthesis of (±)-Leucolusine and (±)-7-epi-Leucolusine – A Preliminary Report

Herein we report a four-step, unoptimized total synthesis (±)-leucolusine and its C7 diastereomer. Features of the synthesis include an improved two-step synthesis of a pivotal indole-lactam-alcohol intermediate, first synthesized by Dixon, and subsequent reductive cyclization to form the tetracyclic core of the natural product. We developed a one-pot oxidation of the pendant indole to access the 3-hydroxy-2-oxindole core of leucolusine directly, furnishing the natural product in only four overall steps. This preliminary report aims to disclose our evolving strategy toward leucolusine and related alkaloids. In the future, we intend to follow up on this report with a fully optimized synthetic route, including efforts toward an enantioselective synthesis of (+)-leucolusine.