2‐Amino‐2‐thiazoline. V. phenylthioureido and phenylureido derivatives of 2‐thiazoline

The reaction of 2‐amino‐2‐thiazoline (I) with phenylisothiocyanate has been reported to give 2‐imino‐3‐phenylthiocarbamoylthiazolidine (II) at low temperatures and l‐phenyl‐3‐(2‐thiazolin‐2‐yl)‐2‐thiourea (III) at ca. 100°. When performed by us, however, this reaction gave only a single mono‐adduct regardless of the temperature. Nmr and chemical evidence indicates that structure III is the correct one. Treatment of I with phenylisocyanate also gave a mono‐adduct which was established to be l‐phenyl‐3‐(2‐thiazolin‐2‐yl)urea (V). Compound I does not form a simple di‐adduct with excess phenylisothiocyanate but does so with phenylisocyanate to give 2‐phenylcarbamoylimino‐3‐phenylcarbamoylthiazolidine (VI). The reaction of III with phenylisocyanate gives 2‐phenylthiocarbamoylimino‐3‐phenylcarbamoylthiazolidine (VII), however, the corresponding reaction of V with phenylisothiocyanate does not give the anticipated product but a mixture of compounds which includes VI and VII.