Regioselective Synthesis Of 4-Aryloxymethyl-2h-Pyrano 3,2-C Benzopyran-5H-One From 1-Aryloxy-4-Coumarinyloxy But-2-Yne^#

Abstract

1-Aryloxy-4-(4′-coumarinyloxy) but-2-yne (1) on refluxing in chlorobenzene gave 4-aryloxymethyl-2H-pyrano 3,2-c benzopyran-5H-one as the single product in almost quantitative yield. All the eight butynes studied underwent 3,3,7 sigmatropic rearrangement at the 4-(4′-coumarinyloxy) propynyl part to give pyranocoumarin derivatives and no furanocoumarin derivative was formed at all.