Cyclocondensation of
5-amino-6-methyl-2-morpholinopyrimidine-4-thiol (
) and
2-bromo-5,5-dimethylcyclohexane-1,3-dione (
) under mild reaction condition afforded
4,7,7-trimethyl-2-morpholino-7,8-dihydro-5H-benzo[b]pyrimido[5,4-e][1,4]thiazin-9(6H)-one (
). The
1H and
13C NMR data of compound (
) are demonstrated that this compound exists primarily in the enamino ketone form. Reaction of compound (
) with
phosphorous oxychloride gave
4-(9-chloro-4,7,7-trimethyl-7,8-dihydro-6H-benzo[b]pyrimido[5,4-e][1,4]thiazin-2-yl)morpholine (
).
Nucleophilic substitution of chlorine atom of compound (
) with typical secondary amines in DMF and K
2CO
3 furnished the new substituted derivatives of 4-(4,7,7-trimethyl-7,8-dihydro-6
H-benzo[
b]pyrimido[5,4-
e][1,4]thiazin-2-yl)morpholine (
). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.