Amine-induced rearrangement of 4-imino-4H-3,1-benzoxazines to 4-quinazolinones via amidine carboxamides

Abstract

Iminobenzoxazines (2) react with pyrrolidine in EtOAc at reflux to give amidine carboxamides (11), which cyclize to quinazolinones (3) on heating in 99:1 MeCN/HOAc. However, both amidines (11d) and (13d) are formed if R 1 = Ar and R2 = Me. Hindered amidine (11f), R1 = Ph, R2 = i-Pr, does not cyclize to give quinazolinone (3f).