Cyclic sulphur-nitrogen compounds and phosphorus reagents: Part XIII¹-Reactions of cyclic sulphur-nitrogen chlorides with Ph₃P-influences of tertiary base, Et₃N and the ring size of the cyclothiazyl chloride on the product formation

Abstract

Similar to the reactions with S₄N₃Cl and S₃N₃Cl_3,triphenylphosphine reacts with five-membered cyclic sulphur-nitrogen chlorides namely, S₃N₂Cl and S₃N₂Cl₂ to give triphenylphosphiniminium chloride, Ph₃P=NH<img src='http://www.niscair.res.in/jinfo/plustwo.gif' border=0>Cl^- as the major product. Maximum yield (ca. 90%) is obtained when triphenylphosphine is reacted with S₃N₂Cl in acetonitrile at room temperature in 2:1 molar ratio. Analogous reactions performed in presence of triethylamine afford two cyclothiazene products containing phosphinimino substituent. The ring size of the S-N chloride seems to determine the nature of phosphiniminocyclothiazenes formed. A rationalization of the results obtained has been attempted.