The synthesis of 5,10‐dihydro‐ and 2,3,5,10‐tetrahydrothiazolo‐[3,2‐ b ] [2,4]benzodiazepines, 1,2,3,4,7,12‐hexahydrobenzothiazolo‐[3,2‐ b ] [2,4] benzodiazepine, and 9,14‐dihydro‐6 H ‐[1]benzothiopyrano‐[4′,3′:4,5]thiazolo[3,2‐ b ] [2,4] benzodiazepine via 1,2,4,5‐Tetrahydro‐3 H ‐2,4‐benzodiazepine‐3‐thione

Catalytic reductive scission of phthalazine (II) utilizing a two‐stage palladium‐Raney nickel procedure afforded o ‐xylene‐α,α′‐diamine (III) in 97% yield. Treatment of III with carbon disulfide gave [ o ‐(aminomethyl)benzyl]dithiocarbamic acid (IV), which upon thermal cyclization furnished 1,2,4,5‐tetrahydro‐3 H ‐2,4‐benzodiazepine‐3‐thione (V). Reaction of V with 1,2‐dibromoethane, chloro‐2‐propanone, ethyl 2‐chloroacetoacetate, ethyl chloroacetate, and ethyl 2‐bromohexanoate gave 2,3,5,10‐tetrahydrothiazolo[3,2‐ b ][2,4]benzodiazepine (VII) and substituted 5,10‐dihydrothiazolo[3,2‐ b ][2,4]benzodiazepines (Villa and b, IX, and X), respectively. Condensation of V with 2‐chlorocyclohexanone and 3‐bromothiochroman‐4‐one afforded 1,2,3,4,7,12‐hexahydrobenzothiazolo[3,2‐ b ][2,4]benzodiazepine (XII) and 9,14‐dihydro‐6 H ‐[1]benzothiopyrano[4′,3′:4,5]thiazolo[3,2‐ b ][2,4]benzodiazepine(XIll). None of the compounds possessed appreciable biological activity.