Novel regioselective ring closing ene-yne metathesis provided an efficient access to different substituted 1-benzazepine scaffolds. The reported synthetic approach could also be used as a powerful tool for the selective formation of a highly functionalizable 2-benzazepine core. This synthetic protocol was even proved to be an efficient way to obtain a functionalizable benzazocine derivative. By modifying the structure of the starting materials, the optimized cyclization finally proved to be a suitable technique to obtain five- and six-membered lactams, enhancing the synthetic application of our method. Five- and six-membered lactams were efficiently prepared by ring-closing metathesis involving the loss of ethylene moiety and affording highly functionalizable compounds showing both electron-withdrawing substituents and electron-donor groups.
Key words
ring closing ene-yne metathesis - ring closing ene-ene metathesis - Grubbs catalysts - nitrogen heterocycles - regioselective reactions - benzazepine scaffolds - lactams
