A Facile Route to Phenylselanyl Substituted Pyrano[3,2-c]chromenes

The synthesis of a new family of phenylselanyl substituted pyrano[3,2-c] chromenes is presented. The cyclocondensation reaction of 3-formylchromones 1 with phenylselanylacetic acid 2 in acetic anhydride under mild conditions gave the novel 3-(phenylselanyl)-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl acetates P1 in 80% yield. Further treatment of acetates P1 with ethanolic or aqueous medium led to the corresponding 5-ethyloxy-3-(phenylselanyl)-2-oxo-2H,5H-pyrano[3,2-c]chromen P3 and 3-(phenylselanyl)-2H,5H-pyrano[3,2-c]chromen-5-ol P4 , respectively. We found the reaction of phenylselanylacetic acid with arylcarbaldehydes in acetanhydride at room temperature yielded the corresponding 2-(phenylselanyl)cinnamoyl acid P5. This reaction at elevated temperature, under reflux or in the solventless mixture at 180oC led only to the diphenyl-diselane P6 and a pitch polymer.