Investigation of Diels-Alder Reaction of 7-Substituted 4-Styrylcoumarins with Symmetrical Dienophiles Leading to 3,4-Annulated Coumarins
作者:Kailas K. Sanap、Rama S. Kulkarni、Shriniwas D. Samant
DOI:10.1002/jhet.1502
日期:2013.5
The thermal [4 + 2] cycloaddition reaction of 7‐substituted 4‐styrylcoumarins with N‐phenylmaleimide and tetracyanoethylene in nitrobenzene under reflux conditions rapidly gives 3,4‐annulated coumarins as the Diels–Alder adducts. The position of the surviving double bond was determined on the basis of NMR and supported by energies of the possible structures. The effects of the 7‐substituent and the