Structure and condensation reactions of 2,3-dihydrofuro[3,2-c]coumarin-3-one

Furo[3,2-c]coumarins carrying carbon substituents at C-2 and/or C-3. Isolation, biological activity, synthesis and reaction mechanisms

“…96 A series of other 4-hydroxycoumarins behaved similarly. The products were then exposed to 1 M HCl, giving almost quantitative yields of the corresponding furo[3,2-c] coumarins (98).…”

“…An alternate and related sequence toward 98 which does not resort to the use of aldehydes has been reported by Traven et al 97 This group prepared the chloroacetyl ester of 4-hydroxycoumarin (99), effected its Fries rearrangement to 100 and then cyclized the chloromethyl ketone to the furanone 101. 98 Reduction of the ketone moiety followed by dehydration of the resulting alcohol 97 furnished the tricyclic nal product 98. On the other hand, the Knoevenagel reaction of the furanone 101 with different aromatic aldehydes provided the corresponding crotonization products 102, which exhibited strong uorescence, whereas reaction with aromatic amines afforded the corresponding imines, in tautomeric equilibrium with the related enamines.…”