ChemInform Abstract: Quinazolin‐2‐ones Having a Spirohydantoin Ring. Part 3. A General and Efficient Synthesis of 3′‐Substituted Spiro(imidazoline‐4,4′(1′H)‐ quinazoline)‐2,2′,5(3′H)‐triones.

Abstract

Quinazolin-2-ones Having a Spirohydantoin Ring. Part 3. A General and Efficient Synthesis of 3'-Substituted Spiro(imidazoline-4,4'(1'H)quinazoline)-2,2',5(3'H)-triones.-The 1-carbamoylisatins (III), prepared by reaction of isatin (I) with the isocyanates (II), undergo cyclocondensation with 2-ethylisothiourea hydrobromide (IV) to form the quinazolines (V). These are directly cyclized to produce the spiro compounds (VI) mentioned in the title. -(YAMAGISHI, M.; OZAKI, K.; YAMADA, Y.; DA-TE, T.; OKAMURA, K.; SUZUKI, M.; Chem.