A Base-Mediated Approach Towards Dihydrofuro[2,3-b]Benzofurans from 2-Nitrobenzofurans and 1,3-Dicarbonyls

A straight-forward approach for the synthesis of a dihydrofuro[2,3-b]benzofuran derivatives has been achieved through a base-mediated Michael addition of 1,3-dicarbonyls to 2-nitrobenzofurans followed by intramolecular cyclization. A variety of 1,3-dicarbonyls, including cyclic as well as trifluoromethylated ones, have been subjected to react with 2-nitrobenzofurans under optimal conditions, and the respective dihydrofuro[2,3-b]benzofurans could be accessed in moderate to excellent yields.     

Oxidant‐Controlled Catalytic Transformations of Phenols with Unexpected Cleavage of Aromatic Rings

Oxidative transformations of phenols have attracted significant attention of chemists due to their importance in biological process and organic synthesis. In contrast to the relatively well‐developed oxygenation and coupling reactions of phenols, the highly efficient and selective oxidative ring cleavage of phenols is under‐represented. This work describes a novel CuCl‐catalyzed tandem homocoupling/skeletal rearrangement of phenols that realizes the cleavage of the phenol ring by using air or Ag₂CO₃ as the oxidant. Interestingly, simply changing the oxidant to K₂S₂O₈ results in the oxidative coupling/cyclization of phenols to give dibenzofurans. These results set an important precedent of oxidant‐controlled catalytic transformations of phenols.     

One-pot multicomponent synthesis of functionalized 2,5-disubstituted-1,3,4-thiadiazine derivatives

An atom-efficient and environmentally friendly approach to the synthesis of 2,5-disubstituted-1,3,4-thidiazine derivatives has been developed. These compounds were synthesized by a reaction of 2-(2-bromoacetyl)benzofuran and thiocarbohydrazide with various aryl aldehydes, acetylacetones, and pthalic anhydrides in good yields. The advantages of this methodology are mild reaction conditions, easy workup procedure, clean reaction profile, shorter reaction time, and a wide range of substrate applicability. The structures of all synthesized compounds were confirmed from their analytical and spectral data.     

Halogen Dance on 2-Iodobenzofuran and 2-Iodobenzothiophene and Related Reactions

When 2-iodobenzofuran was treated sequentially with lithium 2,2,6,6-tetramethylpiperidide in tetrahydrofuran at −50 °C and an aldehyde, the 2-substituted 3-iodobenzofuran resulting from the halogen dance was the only isolated product. However, from 2-iodobenzothiophene, these conditions led to mixtures in which the 2-substituted 3-iodobenzothiophene was always accompanied by the 2-substituted benzothiophene. The use of 2-bromobenzothiophene as a catalyst made it possible to significantly reduce this competitive dehalogenation. To confirm the halogen dance reaction, the products were unambiguously synthesized by using direct halogenations and deprotolithiation-trapping sequences as key steps. Our efforts to access 2,7-disubstituted and 7-substituted derivatives of benzofuran and benzothiophene have also been reported.     

Synthesis of benzofurans through coupling of dienylacetylenes with carbene complexes: total synthesis of egonol

The reaction of various carbene complexes with dienylacetylenes has been examined. The reaction has been used as the cornerstone for the preparation of the nor-neolignan natural product egonol in five steps from readily available components. In most examples of the carbene-alkyne coupling, the reaction proceeds to form benzofuran derivatives. In the case of one highly functionalized terminal alkyne, a competing rearrangement/cyclization process occurs in preference to the carbene coupling process. The use of silylated alkynes subverts this process.     

Synthesis,characterization, and investigations of antimicrobial activity of benzopyrans,benzofurans and spiro[4.5]decanes

In this study, the radical cyclization reactions of cyclic 1,3-dicarbonyl compounds (1a–c) and α,β-unsaturated alcohols (2a–d) through Mn(OAc)₃ were performed. A series of biologically interesting dihydropyrans (3–5) and dihydrofurans (6–18) were synthesized as a result of these reactions. Spiro compounds (19–20) were obtained from the reactions of 1,3-dicarbonyl compounds and (E)-2,4-diphenyl-but-3-en-2-ol (2e). The unique structure of compound 19 was also confirmed by X-ray crystallography. In addition, the antibacterial activities of synthesized compounds were screened against some bacteria. Their zone diameters showed better results than some known antibiotics.     

A three-dimensional chemical phase pharmacophore mapping,QSAR modelling and electronic feature analysis of benzofuran salicylic acid derivatives as LYP inhibitors

Lymphoid tyrosine phosphatase (LYP), encoded by the PTPN22 gene, has a critical negative regulatory role in T-cell antigen receptor (TCR) and emerged as a promising drug target for human autoimmune diseases. A five-point pharmacophore with two hydrogen bond acceptors, one hydrogen bond donor and two aromatic ring features was generated for a series of benzofuran salicylic acid derivatives as LYP inhibitors in order to elucidate their anti-autoimmune activity. The generated pharmacophore yielded a significant 3D-QSAR model with r² of 0.9146 for a training set of 27 compounds. The model also showed excellent predictive power with Q² of 0.7068 for a test set of eight compounds. The investigation of the 3D-QSAR model has revealed the structural insights which could lead to more potent analogues. The most active and inactive compounds were further subjected to electronic structure analysis using density functional theory (DFT) at B3LYP/3?21^?G level to support the 3D-QSAR predictions. The results obtained from this study are expected to be useful in the proficient design and development of benzofuran salicylic acid derivatives as inhibitors of LYP.