REACTION OF 5,5-DIPHENYL-2-THIOHYDANTOIN WITH 1,3-DIBROMOPROPANE. CRYSTAL AND MOLECULAR STRUCTURE OF 2,3,4,5-TETRAHYDRO-6,6-DIPHENYLIMIDAZO-THIAZINE-7(6H)-ONE

Article abstract of DOI:10.1016/0040-4020(80)80063-9

The reaction between the potassium salt of 5,5-diphenyl-2-thiohydantoin (1) and 1,3-dibromopropane carried out in DME under anhydrous conditions has been found to give two isomeric diphenylimidazothiazines 2 and 3.When the reaction of 1 with 1,3-dibromopropane was performed in protic solvents (EtOH, HOH, NaOH) 2 and 3-(3-mercaptopropyl)-5,5-diphenylthiohydantoin (4) were formed.The latter is the product of hydrolysis of 3 taking place under the reaction conditions. 2,3,4,5-Tetrahydro-6,6-diphenylimidazo<2,1-b>-thiazine-7(6H)-one (2) crystallises in space group P2₁/n with a=10.812(3), b=14.905(7), c=9.885(4) Angstroem, β=104.91(2) deg.The 5-membered ring in 2 is planar whereas the 6-membered thiazine ring adopts the sofa conformation.