| Summary: | A general procedure for the synthesis of 2-substituted tetrahydro-1,3-thiazepines by MW-assisted cyclization of 4-thioamidobutanols is presented. The acyclic precursors were prepared in high overall yields by an expeditious three-step diacylation/thionation/deprotection sequence from 4-aminobutanol. Microwave-assisted ring closure of 4-thioamido alcohols promoted by trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of several hitherto unreported seven-membered iminothioethers bearing 2-aryl, alkenyl, aralkyl and alkyl substituents. The cyclodehydration reaction is likely to involve an SN2-type displacement and affords good to excellent yields of the desired heterocycles in very short reaction times.
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