Synthesis of 7-Aminocoumarins from 7-Hydroxycoumarins via Amide Smiles Rearrangement

Abstract

N-Substituted 7-aminocoumarins can be synthesized from readily available 7-hydroxycoumarins via alkylation with α-bromoacetamides and subsequent tandem O → N Smiles rearrangement-amide hydrolysis. The key rearrangement sequence proceeds under mild conditions to provide convenient access to various N-alkyl and N-aryl products in moderate to high yields. The process is operationally simple, inexpensive, transition-metal-free, and can be telescoped into a one-pot process.