Novel fluoro substituted benzo[b]pyran with anti-lung cancer activity
6-Fluorobenzo[b]pyran-4-one 1 on condensation with aromatic aldehydes yields 3-arylmethylene-6-fluoro-2,3-dihydrobenzo[b]pyran-4-ones 2 which on treatment with phenylhydrazine and thiourea gives the pyrazole and pyrimidine thione derivatives 3 and 4, resp