1.4- Benzothiazepines 2,3,4,5-tetrahydro— from

The reduced pyrido[4,3-g][l,4]benzothiazepine 133 has been detected by HPLC as a novel metabolite in some human urine samples. It arises from Pictet-Spengler condensation of 5-S-cysteinyldopa with formaldehyde. This chemistry also underpins a facile synthesis of the 2,3,4,5-tetrahydro[l,4]benzothiazepine 134 via reaction of formaldehyde with a cysteinylcatechol . 

The 2,3-benzoxazepin-l-one system (436) is prepared by the reaction of benzonitrile oxide with the benzopyranone (435) (80JCS(P1)846). The tetrahydro-3,2-benzothiazepine 3,3-dioxide (438) was prepared from (437) by intramolecular sulfonamidomethylation (76CC470). 

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