A systematic study on methyl groups in 3-amino-2-methyl-3,4-dihydro-4-oxoquinazoline towards condensation with aldehydes

3-amino-2-methyl-3,4-dihydro-4-oxoquinazoline was prepared by modified Klosa’s method and was in condensed with various aliphatic and aromatic aldehydes in two stages (scheme 1-3). The first molecule of aldehyde reacted with the N-3 amino group and the second molecule reacted with the methyl group at C-2. On hydrolysis the benzylidene group at N-3 gets hydrolysed leaving behind the styrul groups at C-2. This preferential reactivity of the two functional groups at N-3 and C-2 positions was investingated.