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SYNTHESIS OF BENZOFURANS FROM ISOVANILLIN VIA C-PROPENYLATION-O-VINYLATION AND RING-CLOSING METATHES

SYNTHESIS OF BENZOFURANS FROM ISOVANILLIN VIA C-PROPENYLATION-O-VINYLATION AND RING-CLOSING METATHES

  1. Anonymous
    HETEROCYCLES, Vol. 63, No. 8, 2004, pp. 1771 - 1781
    Tzu-Wei Tsai, Eng-Chi Wang, Keng-Shiang Huang, Sie-Rong Li, You-Feng Wang, Yu-Li Lin, and Yung-Hua Chen

    Substituted benzofurans derived from isovanillin were synthesized. 2-Allyl-3-alkoxy-4-methoxyphenol, prepared from isovanillin via the Claisen rearrangement, O-alkylation and Baeyer-Villiger oxidation, were chloroethylated by two-phase reaction to furnish 1-allyl-3-alkoxy-(2-chloroethoxy)-4-methoxybenzenes. The given compounds were treated with potassium tert-butoxide to undergo the isomerization of O-allyl group and dehydrochlorination of 2-chloroethoxy group to efficiently construct the precursors with C-propenyl-
    O-vinyl function for the ring-closing metathesis (RCM) in one pot. Then, the precursors were subjected to RCM to furnish 4,5-O-difunctionalized benzofurans in good over-all yield, respectively.