Boron Trifluoride Etherate-Controlled Reactions of Methyl Enol Ethers: Selective Synthesis of Dihydrofuro[3,2-c]chromenone and Furo[3,2-c]chromenone Derivatives

Abstract

A facile one-step synthetic approach to dihydrofuro[3,2-c]chromenones and furo[3,2-c]chromenones by the reaction of methyl enol ethers with 4-hydroxy coumarin in a metal-free condition is presented. Dihydrofuro[3,2-c]chromenones and furo[3,2-c]chromenones were selectively obtained by controlling the stoichiometry of boron trifluoride diethyl etherate (BF3.Et2O). An unexpected aryl group migration followed by aromatization of furan moiety leading to a variety of furo[3,2-c]chromenone derivatives in good yields is reported.

Evaluation of a panel of furochromenones as the activator and inhibitor of tyrosinase

“…Total 21 compounds described earlier (Khan & Ahmad, 2022), namely, 3b , 3c , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3L , 4a , 4b , 4c , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4L were selected for the study. However, 3b , 3c , 3g , 3i , 3h , 4a , 4j , 4g , could not be dissolved in methanol, isopropanol or DMSO and excluded from the study.…”

“…However, there are only a few reports of furochromenones with substantial anti‐vitiligo activity. We recently reported a synthetic approach to generate a variety of dihydrofuro[3,2‐c]chromenones and furo[3,2‐c]chromenones in a metal‐free condition (Khan & Ahmad, 2022). Among the 21 different dihydrofuro[3,2‐c]chromenones and furo[3,2‐c]chromenones reported (Khan & Ahmad, 2022), we evaluated 13 compounds for their potential as inhibitors or stimulators of tyrosinase in the present study.…”

Copper-Catalyzed Asymmetric Propargylic [3 + 2] Cycloaddition: Synthesis of Enantioenriched Dihydrofuro[3,2-c]coumarins and its Quinolinone and Thiocoumarin Analogues

“…Furo­[3,2- c ]­coumarin is one of the prominent members of the furocoumarin family and contributes as a core skeleton of several bioactive compounds exhibiting significant therapeutic properties, including antifungal, anticancer, anti-inflammatory, and other medicinal applications (Figure ). Consequently, the synthesis of furo­[3,2- c ]­coumarins and their dihydrocompounds has attracted considerable attention. , However, the synthesis of chiral dihydrofuro­[3,2- c ]­coumarin compounds has been less explored, and it primarily relied on organocatalytic Michael-addition-mediated cyclization sequence (Scheme B) . Therefore, developing an efficient asymmetric strategy for synthesizing enantioenriched dihydrofuro­[3,2- c ]­coumarins is still desirable.…”