An Efficient One-pot Synthesis of Substituted 1, 5-benzoxazepines and 1,5-benzothiazepines Using Potassium Dodecatungstocobaltate Trihydrate (PDTC, K5CoW12O40.3H2O) as Heterogeneous Catalyst

An efficient method has been developed for the synthesis of substituted 1,5-benzoxazepines and benzothiazepines under classical heating conditions or microwave irradiation in the presence of an efficient and reusable Potassium Dodecatungstocobaltate Trihydrate (PDTC, K5CoW12O40.3H2O) as heterogeneous catalyst which was found to be highly active and afforded excellent yields. The products 6,8,9 and 10 were synthesized using the starting compounds 4a-d, 1 mol% PDTC and achieved in good yields by reflux (70-80%) as well as microwave conditions (60-70%). The reactions of 17a-e with 7, in the presence of 1 mol % PDTC were refluxed in dry ethanol for 6-8 h to isolate the compounds 18a-e in good yields (70-85%) as syrups.