7-Bromo-3,3-dibutyl-8-methoxy-5-phenyl-2,3-dihydrobenzo[ b][1,4]thiazepin-4(5 H)-one is prepared from 6-methoxybenzo[ d]thiazol-2-amine and 2-(bromomethyl)-2-butylhexanoic acid as the key starting materials via five simple steps including hydrolysis, substitution, condensation, bromination, and aromatic amidation under microwave conditions. This new route has reduced the reaction time and increased the overall yield to 43%. Moreover, the structure of the target product is also confirmed by X-ray crystal analysis, and further studies indicate that the existence of an intramolecular C–H···C g1 non-classical hydrogen bond is effective in stabilization of the crystal structure.