Collect. Czech. Chem. Commun.
1999, 64, 389-407
https://doi.org/10.1135/cccc19990389
Diels-Alder Reactions of Vinyl Derivatives of [1]Benzothieno[3,2-b]furan
Pavel Piheraa, Hana Dvořákováb and Jiří Svobodaa,*
a Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Central Laboratories, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
Abstract
2-Vinyl- (2) and 3-vinyl[1]benzothieno[3,2-b]furan (3) react with dimethyl acetylenedicarboxylate, methyl propiolate, maleic anhydride, or acrylonitrile endo-selectively as dienes to afford new [1]benzothieno[3,2-b][1]benzofuran derivatives 7-20. cis-Anhydrides 13 and 18 were transformed into dimethyl esters 21 and 22, respectively. It was shown that the base-catalyzed hydrolysis of 13 and 18 is accompanied by rearrangement of double bond in 13 and cis/trans isomerization of carboxylic group. Diesters 21 and 22, and nitriles 20 and 24 were aromatized by treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Selective monodecarboxylation of [1]benzothieno[3,2-b][1]benzofuran-8,9-dicarboxylic acid (26) and [1]benzothieno[3,2-b][1]benzofuran-6,7-dicarboxylic acid (27) afforded [1]benzothieno[3,2-b][1]benzofuran-8-carboxylic acid (28) and [1]benzothieno[3,2-b][1]benzofuran-7-carboxylic acid (29), respectively.
Keywords: [1]Benzothieno[3,2-b]furans; Diels-Alder reactions; [1]Benzothieno[3,2-b][1]benzofurans; [4+2]Cycloadditions; Aromatizations; Dienes; Dienophiles.
