Convenient synthesis of 3-methylcoumarins and coumarin-3-carbaldehydes

Rapid, microwave-assisted Baylis-Hillman reactions of substituted salicylaldehydes, followed by one-pot hydrogen iodide-mediated cyclization and reduction of the corresponding adducts, has afforded 3-methylcoumarins in up to 94% yield in the final step. Subsequent microwave-assisted selenium dioxide oxidation of selected 3-methylcoumarins has provided convenient access to the corresponding coumarin-3-carbaldehydes and permitted a significant improvement over the yield obtained using conventional heating. © Taylor & Francis Group, LLC.