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Synthesis of 2,3-Dihydrobenzofurans

Recent Literature

A bifunctional aminoboronic acid facilitates intramolecular aza- and oxa-Michael reactions of α,β-unsaturated carboxylic acids. The combination of an arylboronic acid with a chiral aminothiourea enables enantioselective conversions to afford the desired heterocycles in high yields and ee’s (up to 96% ee).
T. Azuma, A. Murata, Y. Kobayashi, T. Inokuma, Y. Takemoto, Org. Lett., 2014, 16, 4256-4259.

A highly enantioselective and straightforward intramolecular asymmetric addition of aryl halides to unactivated ketones provides chiral 3-hydroxy-2,3-dihydrobenzofurans with a chiral tertiary alcohol at the C-3 position in good yields and excellent enantioselectivities.
Y. Li, W. Li, J. Tian, G. Huang, H. Lv, Org. Lett., 2020, 22, 5353-5357.

A highly enantioselective palladium-catalyzed iodine atom transfer cycloisomerization of olefin-tethered aryl iodides provides optically active 2,3-dihydrobenzofurans, indolines and chromanes bearing an alkyl iodide group in good yields. The reaction offers use of readily available starting materials, a broad substrate scope, high selectivity, and mild conditions.
Z.-M. Zhang, B. Xu, L. Wu, L. Zhou, D. Ji, Y. Liu, Z. Li, H. Zhang, J. Am. Chem. Soc., 2019, 141, 8110-8115.

A phosphorus(III)-mediated formal [4+1]-cycloaddition of 1,2-dicarbonyls and o-quinone methides provides 2,3-dihydrobenzofurans. Subtle steric interactions involved in the [4+1]-cycloannulation have an impact on yield and stereoselectivity in dihydrobenzofuran formation.
K. X. Rodriguez, J. D. Vail, B. L. Ashfeld, J. Zhu, Org. Lett., 2016, 18, 4514-4517.

Fluoride-induced desilylation of 2-bromo-1-{2-[(triisopropylsilyl)oxy]phenyl}ethyl nitrate enables a regioselective one-pot synthesis of 3-substituted 2,3-dihydrobenzofurans via generation of o-quinone methides followed by Michael addition of different C, N, O, and S nucleophiles, and intramolecular 5-exo-tet elimination of a bromide anion. The method has potential synthetic applications in drug discovery.
A. k. Shaikh, G. Varvounis, Org. Lett., 2014, 16, 1478-1481.