A new approach to benzofuran synthesis: Lewis acid mediated cycloaddition of benzoquinones with stilbene oxides

Catalyst-Free Synthesis of Benzofuran Derivatives from Cascade Reactions between Nitroepoxides and Salicylaldehydes

Different benzofuran derivatives are synthesized via a catalyst-free reaction between nitroepoxides and salicylaldehydes. In the employed methodology, K₂CO₃ and DMF have been used at 110 °C, and the reactions were completed after 12 h in 33-84% yields. The highest yields were obtained using 3-nitrosalicylaldehyde. Finally, a plausible mechanism was proposed for the reaction, and some evidence was provided for this mechanism such as the detection of released acetate anion (using FTIR) and isolation and structure determination of the critical intermediate.

Synthesis and Application of 1,2-Aminoalcohols with Neoisopulegol-Based Octahydrobenzofuran Core

A library of 1,2-aminoalcohol derivatives with a neoisopulegol-based octahydrobenzofuran core was developed and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The allylic chlorination of (+)-neoisopulegol, derived from natural (–)-isopulegol followed by cyclization, gave the key methyleneoctahydrobenzofuran intermediate. The stereoselective epoxidation of the key intermediate and subsequent oxirane ring opening with primary amines afforded the required 1,2-aminoalcohols. The ring closure of the secondary amine analogues with formaldehyde provided spiro-oxazolidine ring systems. The dihydroxylation of the methylenetetrahydrofuran moiety with OsO₄/NMO (4-methylmorpholine N-oxide) resulted in the formation of a neoisopulegol-based diol in a highly stereoselective reaction. The antimicrobial activity of both the aminoalcohol derivatives and the diol was also explored.

Design, synthesis and antitumor activity of novel 8-substituted 2,3,5,6-tetrahydrobenzo[1,2-b:4,5-b′]difuran imidazolium salt derivatives

A series of novel 8-substituted 2,3,5,6-tetrahydrobenzo[1,2-b:4,5-b′]difuran imidazolium salt derivatives were synthesized and their antitumor structure–activity relationship studies were reported.

Strategies for the Synthesis of 2,3-Dihydrobenzofurans

This article gives an overview of synthetic approaches to the 2,3-dihydrobenzofuran ring system with an emphasis on recently developed methods. The synthetic approaches are classified according to the key bond(s) formed during the construction of the dihydrobenzofuran skeleton, and approaches of relevance to the synthesis of natural products are highlighted.

A Facile Synthesis of 2, 3-Dimethoxy-5-Methyl-1, 4-Benzoquinones

Several 2, 3-dimethoxy-5-methyl-1, 4-benzoquinones substituted at the C-6 position with alkoxy methyl groups were prepared by a reaction sequence starting from 2, 3, 4, 5-tetramethoxytoluene (alkoxy methyl) via a Blanc chloromethylation reaction, Williamson reaction and oxidation. The method provided a good yield of 2, 3-dimethoxy-5-methyl-1, 4-benzoquinones and is suitable for the synthesis of other benzoquinone analogues.

Design, synthesis and cytotoxic activities of novel hybrid compounds between dihydrobenzofuran and imidazole

A series of novel hybrid compounds between dihydrobenzofuran and imidazole has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that substitution of the imidazolyl-1-position with an electron-donating dihydrobenzofuran, and the imidazolyl-3-position with a naphthylacyl or electron-rich phenacyl group, were vital for modulating cytotoxic activity.