Microwave-assisted cyclization under mildly basic conditions: Synthesis of 6 h -benzo [c] chromen-6-ones and their 7,8,9,10-tetrahydro analogues

Aryl 2-bromobenzoates and aryl 2-bromocyclohex-1-enecarboxylates are cyclized by microwave irradiation in dimethylformamide in the presence of K₂CO₃ to give the corresponding 6H-benzo[c]chromen-6-ones and their 7,8,9,10-tetrahydro analogues, respectively, in 50-72% yields. Aryl 3-bromoacrylates are also converted into 2H-chromen-2-ones under the employed conditions.