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Updated: Oct 3, 2026

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
Published on: December 16, 2019
General Synthesis of Polysubstituted Benzo[b]furans
Alan R. Katritzky1, Clara N. Fali, Jianqing Li
1Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200.
Abstract:
2-(Benzotriazol-1-ylmethyl)furans 4a-c, on treatment with n-BuLi followed by various alpha,beta-unsaturated ketones and aldehydes, gave the adducts 6a-f which underwent intramolecular cyclization to form substituted benzo[b]furans 10a-f. Lithiation and subsequent alkylation of 4a-c afforded intermediates 8a-c, which underwent similar transformations with alpha,beta-unsaturated ketones or aldehydes to give the corresponding polysubstituted benzo[b]furans 7a-c. o-Iodophenol (11) with 1-propargylbenzotriazole (1) in the presence of (PPh(3))(2)PdCl(2), CuI, and Et(3)N gave 2-(benzotriazol-1-ylmethyl)benzo[b]furan (12). The benzotriazolyl-CH(2) side chain of 12 was further elaborated by (i) alkylation with trans-cinnamaldehyde to give the adduct 14, followed by intramolecular cyclization to give dibenzofuran 17; (ii) alkylation with benzyl bromide followed by elimination or nucleophilic displacement of the benzotriazolyl moiety with Grignard reagent and subsequent dehydrogenation to give 2-alkenylbenzofurans 15 or 20, respectively; (iii) alkylation with (CH(3))(3)CCHO followed by low-valent titanium-promoted olefination to give olefin 19; and (iv) alkylation with benzaldehyde followed by Lewis acid catalyzed pinacol type reaction to give 18.
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