I. Yamamoto et al., HALOGENOVINYL SULFONES .5. SYNTHESIS OF A DIBENZOPYRAN DERIVATIVE FROM AN INTRAMOLECULAR DIELS-ALDER REACTION, Phosphorus, sulfur and silicon and the related elements, 116, 1996, pp. 203-210
Reaction of o-(1,3-pentadienyl)-phenol 3 with 1,3-dichloro-2-phenylsul
fonylpropane 2 in the presence of triethylamine gave o-(1,3-pentadieny
l)-phenyl (2 phenylsulfonyl)-2-propenyl ether 4 in 91-100% yields, whi
ch underwent intramolecular Diels-Alder reactions to afford dibenzopyr
an derivatives.