Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition
Maryna Mazur, Oleksii Zhelavskyi, Eugene Zviagin, Svitlana V. Shishkina, Владимир И. Мусатов, Максим А. Колосов, Elena H. Shvets, Anna Yu. Andryushchenko, Валентин А. Чебанов
Abstract
A novel catalyst-free synthetic approach to 1,2,3-triazolobenzodiazepinones has been developed and optimized. The Ugi reaction of 2-azidobenzaldehyde, various amines, isocyanides, and acids followed by microwave-assisted intramolecular azide-alkyne cycloaddition (IAAC) gave a series of target heterocyclic compounds in moderate to excellent yields. Surprisingly, the normally required ruthenium-based catalysts were found to not affect the IAAC, only making isolation of the target compounds harder while the microwave-assisted catalyst-free conditions were effective for both terminal and non-terminal alkynes.