REACTION OF 5,5-DIPHENYL-2-THIOHYDANTOIN WITH 1,4-DIBROMOBUTANE. THE CRYSTAL AND MOLECULAR STRUCTURE OF 2,3,4,5-TETRAHYDRO-7,7-DIPHENYLIMIDAZO-[2,1-b]-THIAZEPINE-8(7H)-ONE

Abstract

The reaction of 5,5-diphenyl-2-thiohydantoin (1) (DPTH) or its potassium salt (DPTH-K) with 1,4-dibromobutane gave two isomeric bicyclic products: 2,3,4,5-tetrahydro-7,7-diphenylimidazo-[2,1-b]-thiazepine-8(7H)-one (6) and 2,3,4,5-tetrahydro-8,8-diphenylimidazo-[2,1-b]-thiazepine-7(8)-one (7) in different ratios depending on the reaction conditions: [DPTH-K, EtOH, N-ethylpiperdine; phase transfer catalytical conditions: DPTH-K, Et₃N, benzene/water or DPTH acetone/K₂CO₃]. Compound (6) crystallizes in the space group P2₁/c with a = 10.4624(2), b = 8.3643(1), c = 18.4371(3) Å β = 96.3(1)°. The 7-membered thiazepine ring in (6) adopts a disordered chain conformation. The discussion of some physico-chemical properties and some factors showing the influence on the yield and ratios of isomeric compounds [(2), (3)], [(4), (5)] and [(6), (7)], obtained in the alkylation of DTPH (1) with dibromoalkanes, has been carried out.