Benzofuran Derivatives. II. Synthesis of 2,3-Dihydrobenzofurans from Ethyl 2-Acylphenoxyacetates

Article abstract of DOI:10.1246/bcsj.58.2821

Ethyl 3-alkyl-3-hydroxy-5-nitro-2,3-dihydro-2-benzofurancarboxylates were obtained from the reaction of ethyl 2-acyl-4-nitrophenoxyacetates with potassium hydroxide in dry dioxane.The relative ratios of the cis and trans isomers with respect to C-2 and C-3 stereochemistry varied according to the structure of the acyl group.When the acyl group was acetyl, propionyl, or isobutyryl group, the cis isomers (2-alkoxycarbonyl groups and 3-hydroxyl groups are cis) were exclusively obtained in high yields.On the other hand, a nearly equimolecular amount of the cis and trans isomers was obtained from the reaction of 2-formyl derivatives under the same conditions.