Chemodivergent Synthesis of 1,3-Benzoxazines, Indolin-3-ols, and Indoles from the Designer Amides: Applications to the Synthesis of Phenanthridine Natural Products

Abstract

A chemodivergent synthesis of 1,3-benzoxazines, indolin-3-ols, and indoles has been conceptualized from readily accessible 2-bromoacetylphenyl benzamides. The strategy emanates from the NaBH₄-mediated reduction of the designer amides, triggering an intramolecular cyclization cascade and furnishing three distinct classes of heterocycles with high precision. A unified synthesis of phenanthridine natural products was also accomplished to work out the utility of this strategy. Broad substrate scope, operational flexibility, and successful implementation at the gram-scale level are notable highlights of this strategy.