Synthesis of Clausenal from Carbazole Using Sequential C–H Borylations

Abstract

Carbazoles represent an enormous family of alkaloids with a vast array of biological properties, inspiring dozens of total syntheses of these natural products. The strategies used to synthesize carbazoles are overwhelmingly reliant on one or more (hetero)cyclization reactions. Conceptually, the simplest way to construct substituted carbazoles would be to subject a simple carbazole core to several C–H functionalization reactions, negating the need for any cyclization steps. In this regard, this thesis describes the successful development of a conceptually disparate approach to carbazole synthesis. By subjecting readily available, cheap carbazole to sequential C-H functionalization reactions, the synthesis of the natural product clausenal was achieved in a route devoid of cyclization reactions. The spectroscopic data for the natural product was in full agreement with the literature.