Ga(OTf)3-promoted condensation reactions for 1,5-benzodiazepines and 1,5-benzothiazepines

Condensation reactions of o-phenylenediamine and two equivalents of acetophenone under gallium(III) triflate catalysis produce biaryl-substituted 1,5-benzodiazepines. Similar reactions of o-phenylenediamine or o-aminothiophenol and o-hydroxy chalcones lead to formation of functionalized 1,5-benzodiazepines and 1,5-benzothiazepines in good to excellent yields. The ortho-hydoxy group of chalcones is crucial for this unprecedented condensation process.