Diels-Alder trapping of in situ generated dienes from 3,4-dihydro-2H-pyran with p-quinone catalysed by p-toluenesulfonic acid.

Diels-Alder trapping of in situ generated dienes from 3,4-dihydro-2H-pyran with p-quinone catalysed by p-toluenesulfonic acid.