Cyclization of 2‐benzoylamino‐N‐methyl‐thiobenzamides to 3‐methyl‐2‐phenylquinazolin‐4‐thiones

Acylation of 2‐amino‐N‐methyl‐thiobenzamide with substituted benzoyl chlorides has been used to synthesize the corresponding 2‐benzoylamino‐N‐methylthiobenzamides. Subsequent sodium methoxide‐catalyzed ring closure gives the corresponding 3‐methyl‐2‐phenylquinazoline‐4‐thiones. These compounds were characterized by means of their ¹H‐ and ¹²C‐NMR spectra. The kinetics of the cyclization reaction has been followed with UV‐VIS spectroscopy at 100 °C in methanolic solutions of sodium methoxide.