Electrogenerated base-promoted synthesis of tetrahydrobenzo[b]pyran derivatives

An efficient and convenient synthesis of tetrahydrobenzo[b]pyrans is described, using an electrogenerated base of the anion of malononitrile in a one-pot, three component condensation of an aromatic aldehyde, an active methylene compound and dimedone. The reaction is carried out at room temperature in acetonitrile with the use of a sacrificial magnesium anode in a single-compartment cell.