Synthesis of 4(3H)‐quinazolinones from derivatives of methyl 2‐isothiocyanatobenzoate

Abstract
EthylN‐(2‐methoxycarbonylphenyl)thiocarbamate (2),N‐(2‐ethoxycarbonylphenyl)‐4‐methoxythiobenz‐amide (3b), and 2‐(4‐methoxyphenyl)‐4H‐3,1‐benzothiazin‐4‐one (4a), react with nucleophilic reagents containing at least one primary amino group to yield a variety of 2‐substituted and 2,4‐disubstituted 4(3H)quinazolinones, as well as some tricyclic and tetracyclic products.