Compound

4a

4b

4c

4d

4e

-R

-H

P-Br

P-OCH3

P-CH3

P-NO2

Compound

5a

5b

5c

5d

5e

-R1

-H

P-Br

P-OCH3

P-Cl

M-NO2

Table 1: 2,6-dihydro-2,6-diimino-4,8-bis (substituted) pyrimido [2,1b][1,3] thiazine-3,7- dicarbonitrile.