Synthesis of triazolo-fused benzoxazepines and benzoxazepinones via Passerini reactions followed by 1,3-dipolar cycloadditions

Azidobenzaldehydes can be used in Passerini three-component condensations to synthesize small collections of triazolo-fused heterocycles in an efficient and combinatorial fashion upon post-condensation azide-alkyne cycloadditions. Triazolo-fused benzoxazepinones were obtained in moderate to good overall yields with a concise two-step protocol. Triazolo-fused benzoxazepines were instead prepared by means of a longer, yet straightforward route comprising a Passerini reaction, hydrolysis of the ester moiety, O-alkylation with propargylic bromides, and 1,3-dipolar cycloaddition