A facile route to phenyl, phenylsulfanyl and phenylselanyl substituted pyrano[3,2-c]chromenes

The synthesis of phenyl. phenylsulfanyl and phenylselanyl substituted pyrano[3,2-clchrorneiles 4 is accomplished via cyclocondensation of 4-oxo-4H-chromen-3-carbaldehydes I with appropriately substituted acetic acids 2 Under mild conditions Further treatment of 4 with alcohol or water led to 5-alkoxy- and 5-hycli-oxy-2H,5H-pyrano[3,2-c]chromen-2ones 5 and 6, respectively Acid and thermal catalysed rearrangement of 4-6 gave 5-hydroxypyrano[2,3-b]chromen-2(10aH)-ones 7 and their subsequent substitution led to 5-alkoxyderivatives 8 Reaction of 4 With alludes led to 5-acylamino or 5phenylsulfonarnino Substituted 2H,5H-pyrano[3,2-c]chromen-2-ones 9 Reactions were performed under heating or microwave irradiation 13 2009 Published by Elsevier Ltd