Recent Advances Towards the Synthesis of Dihydrobenzofurans and Dihydroisobenzofurans

Abstract

The 2,3-dihydrobenzofuran heterocyclic systems are found in various biologically active natural and pharmaceutical products of biological relevance such as Phalarine, Rocaglamide, and Furaquinocin A. The interest in the study of 2,3-dihydrobenzofurans is constantly increasing because of their numerous biological properties such as anti-tumor, anticancer, anti-tubercular, and anti-malarial activities. Different methods have been established towards the synthesis of 2,3dihydrobenzofurans involved via intra-and inter-molecular reactions. Besides, the 1,3-dihydroisobenzofuran structure has been identified as a fundamental nucleus in many natural products, bioactive compounds, and functional molecules (e. g., Pestacin, Isopestacin, Citalopram, Xylarinol B, Matriisobenzofuran, Thunberginol F7-O-β-D-glucopyranoside). On the other hand, 1,3-disubstituted isobenzofurans are powerful structural motifs with a wide range of biological activities, like anti-inflammatory, anti-histaminic, and anti-HIV. In the last few years, a decent number of diligent synthetic approaches have been demonstrated toward synthesizing 1,3-disubstituted isobenzofurans. This review focuses on the effective synthetic routes developed to construct 2,3-dihydrobenzofurans and 1,3-dihydroisobenzofurans and their applications in recent years.

Visible-light-induced cascade reaction: a sustainable approach towards molecular complexity

“…Various natural products and synthetic medicines contain this component, which unlocks new potential for further synthetic applicability. 45 In Nov 2020, Sun and co-workers 46 developed a strategy for synthesizing sulfonyl-bearing DHB scaffolds via radical cascade annulation under visible-light irradiation. As shown in Scheme 25, the exploitation of 2-alkynylarylethers ( 25a , 0.2 mmol) and sodium sulfinates ( 25b , 0.4 mmol) in conjunction with metal photocatalyst Ir[(ppy) 2 (dtbbpy)]PF 6 (2 mol%), additive AcOH & water and solvent DMF under 30 W blue LED irradiation and N 2 atmosphere at room temperature for 24 h provided the intended product 25c with up to 78% yield.…”

Application of sulfonium and sulfoxonium ylides in organocatalyzed asymmetric reaction

“…Chiral 2,3-dihydrobenzofurans are ubiquitous and important ring structures embedded in some natural products and synthetic drugs with diverse bioactivities. Consequently, the synthesis of structurally diverse 2,3-dihydrobenzofuran compounds via a catalytic asymmetric manner has attracted tremendous attention from synthetic chemists [59,60] . In 2015, Lei et al reported a facile synthesis of racemic 2,3-dihydrobenzofurans via formal [4 + 1] cyclization of sulfonium ylides and in situ generated ortho-quinone methides (o-QMs) from O-silylated phenols [61] .…”

Photoinduced Cascade Reactions of 2-Allylphenol Derivatives toward the Production of 2,3-Dihydrobenzofurans

“…Importantly, the 2,3-dihydrobenzofuran core is widely present in natural compounds and biologically active drugs . This class of products displays various biological activities, such as anti-HIV, antimalarial, anticancer, antinociceptive, anti-inflammatory, antifungal, and antibacterial activities. , …”