New efficient synthesis of 2-alkylthio-5-benzylidene-4H-imidazolin-4-ones

摘要

4H-Imidazolin-4-ones are important heterocycles having biological and pharmaceutical activities, and some 2-alkylthioimidazolinones show significant fungicidal activities. However, most of the 2-alkylthioimidazolinones reported are of the 5,5-disubstituted type and were generally synthesized from corresponding alpha-aminoacetic acid. Unfortunately, 5-benzylidene 2-alkylthioimidazolinones cannot be prepared by this general method for the corresponding starting material would be unstable vinyl amino acetic acids. Recently, we became interested in the synthesis of biologically active imidazolinones via tandem aza-Wittig reaction and now report a new efficient preparation of 5-benzylidene-2-alkylthioimidazolinones from the stable vinyliminophosphorane 1.