Synthesis of Benzofurans from Ketones and 1,4-Benzoquinones

Article abstract of DOI:10.1002/adsc.201600048

Benzofuran derivatives can be synthesized through the sequential Michael addition and cyclization of 1,3-dicarbonyl compounds with 1,4-benzoquinones. However, ketones are rarely used in this reaction because of their low nucleophilicities. In this study, this problem was solved by utilizing triethyl orthoformate, which enabled the formation of a vinyl ethyl ether as an additive. As a result, the nucleophilicity of ketones increased. Many important 5-hydroxybenzofuran derivatives, which were not readily available by synthesis in the past, were also prepared via these newly established reactions. (Figure presented.) .