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 6 H-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 2 H-chromen-2-ones under the employed conditions.