The reaction of the potassium salt of 5,5-diphenyl-2-thiohydantoin with 1,3-dibromopropane and triethylamine carried out under phase transfer catalytic conditions gave almost quantitatively two isomeric diphenylimidazothiazine 2 and 3 in a ratio ca 1:2. 2,3,4,5-Tetrahydro-7,7-diphenylimidazo- [2,1-b]-thiazine-6(7H)-one (3) crystallises from DMSO in the space group P212121 with a = 8.488(3), b = 11
Kiec-Kononowicz, Katatzyna; Zatorski, Andzrej; Karolak-Wojciechowska, Janina, Phosphorus, Sulfur and Silicon and the Related Elements, 1989, vol. 42, p. 191 - 200