Regioselective synthesis of o-triazolyl-1,5-benzodiazepin-2-ones and o-isoxazolyl-1,5-benzodiazepin-2-ones via copper-catalyzed 1,3-dipolar cycloaddition reactions

A series of novel O-triazolyl-1,5-benzodiazepin-2-ones 6a–o and O-isoxazolyl-1,5-benzodiazepin-2-ones 7a–o was synthesized via a Cu(I)-catalyzed 1,3-dipolar alkyne–azide coupling reaction of N-substituted-1,5-benzodiazepine–alkyne derivatives 3a–c with various aromatic azides 4a–e and nitrile oxides 5a–e, respectively. The chemical structures of synthesized compounds were determined using ¹H NMR, ¹³C NMR, heteronuclear multiple bond correlation (HMBC), high-resolution mass spectra, as well as elemental analysis and was further confirmed by an X-ray diffraction analysis for compound 7d.