The present disclosure provides a process for preparation of 3,6-dichlorocyano pyrazine, 3,6-dioxopiperizine derivatives and production of favipiravir via ammonia or amine-mediated cyclization and chlorination using POCl3 in the presence of pyridine or PCl5. [Formula] wherein in 3,6-dioxopiperazine derivatives (III), X is CN, CONH2 or COOR2', R1, R2 and R2' are individually selected from H, C1-C12 alkyl, COOR3 and SO2R3 wherein R3 is substituted or unsubstituted linear or branched lower alkyl.