Collect. Czech. Chem. Commun. 1982, 47, 3055-3061

An-Additions to 2,5-dimethoxy-2,5-dihydrofurans, containing electron-accepting substituents in position 3

Ivan Stibor, Jan Šrogl, Miroslav Janda, Naděžda Piričová and Karel Vlažný

Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


3-Acetyl-2,5-dimethoxy-2,5-dihydrofuran (V) was alkylated in position 4 with lithium dimethylcuprate and lithium dibutylcuprate. The reaction, proceeding with loss of methanol, afforded 4-acetyl-3-methyl-2-methoxy-2,3-dihydrofuran (X) and 4-acetyl-3-n-butyl-2-methoxy-2,3-dihydrofuran (XI), respectively. Addition of sodium salt of diethyl malonate gave 3-acetyl-4-bis(ethoxycarbonyl)methyl-2,5-dimethoxytetrahydrofuran (XVII) in 69% yield. Addition of methanol, n-butanol and tert-butyl alcohol to methyl 2,5-dimethoxy-2,5-dihydro-3-furoate (VI) in the presence of the corresponding alkoxides afforded the 4-alkoxy derivatives in 95%, 62% and 56% yield, respectively. Reaction of the compound VI with ethyl lithioacetate led to 3-ethoxycarbonylmethyl-4-methoxycarbonyl-2-methoxy-2,3-dihydrofuran (XVI) arising from the addition product by loss of methanol.