Synthesis and evaluation of 2-chloromethyl-3-N-substituted arylthieno (2,3-d)pyrimidin-4-ones and derivatives for central nervous system depressant activity.

2-Chloromethyl 3-N-substituted arylthieno (2,3-d)pyrimidin-4-ones and derivatives were synthesized by reacting 2-amino-3-carboxanilido-4,5,6,7-tetrahydrobenzo(b)thiophenes (Iabc) with chloroacetyl chloride in dioxane and by cyclizing the open chain 3-substituted carboxanilido-2-(omega-chloroacetamido)-4,5,6,7-tetrahydrobe nzo(b)thiophenes (IIabc) under acidic condition. The compounds were characterized by their spectral data and screened for central nervous system depressant activity. The compounds IIIabc and Vabc have shown marked sedative action.