Synthesis of 7-Allylated Benzofuran Derivatives from o- Allyloxyethynylbenzene via Claisen Rearrangement and TBAF-Catalyzed Annulation

Design, synthesis and biological evaluation of new thiazole scaffolds as potential TRPM8 antagonists

The preliminary results on the development of a viable methodology for the further functionalization of 4-hydroxythiazole derivatives to afford target TRPM8 antagonists are reported. The combined Sonogashira coupling/annulation reactions of the ethyl 2-(3-fluorophenyl)-4-tifluoromethylsulfonyloxy-1,3-thiazole-5-carboxylate have been applied to the synthesis of analogues of the selective blocker of TRPM8 DFL23448. Among all the synthetised derivatives, the most promising compound resulted to be active as TRPM8 blocker (IC50 = 4.06 µM), showing an excellent metabolic stability and no cytotoxic effects. Finally, in silico characterisation of the derivatives showed no violation of the drug-likeness rules.

Three new 3-formyl-2-arylbenzofurans from Itea yunnanensis and their anti-hepatocellular carcinoma effects

Five 3-formyl-2-arylbenzofuran derivatives, including three new compounds (1-3) and two known analogues (4-5), were identified from the 95% EtOH extract of Itea yunnanensis. Extensive spectroscopic analyses were performed for the structure elucidation of all new benzofurans, and single-crystal X-ray diffraction analyses were further employed for the structure verification of iteafuranals C (1) and D (2). In MTT assay, iteafuranal E (3) and iteafuranal A (4) displayed significant growth inhibition effect on SK-Hep-1 cells with IC₅₀ values of 5.365 μM and 6.013 μM, respectively. The colony formation assay of 3 and 4 further confirmed their remarkable inhibitory effect on cell growth. Preliminary mechanism study demonstrated that 3 remarkably down-regulated the phosphorylation level of ERK, which suggested 3 could inhibit cell growth and induce apoptosis of SK-Hep-1 cells by blocking RAS/RAF/MEK/ERK signaling pathway. This study highlighted the potential of 3-fomyl-2-benzofuran derivatives as novel lead compounds to treat Hepatocellular carcinoma.

Recent Achievement in the Synthesis of Benzo[b]furans

BACKGROUND

Benzo[b]furan derivatives are oxygen-containing heterocyclic compounds consisting of fused benzene and furan rings and are present in a large number of natural and non-natural compounds. This class of compounds has a wide spectrum of biological activities, such as antiarrhythmic, anticancer, inflammatory, antioxidant, antimicrobial, and antiviral. Furthermore, benzo[b]furan derivatives have also been applied in various areas, such as organic electroluminescence device materials and organic dyes, photosensitizing material, organic synthesis as building blocks or intermediates. Because of a broad range of applicability, the synthesis of benzo[b]furan derivative has drawn great attention of chemists and many studies on the synthesis of this class of compounds have been reported recently. This review will give an overview of benzo[b]furan preparation based on studies dating back to the year 2012.

OBJECTIVE

In this review, recent development in the synthesis of benzo[b]furans are discussed. There has been increasingly new methodologies for the construction of benzo[b]furans skeleton to improve efficiency or develop environmentally friendly procedures. In some studies, reaction mechanisms were also outlined.

CONCLUSION

Many methods for the synthesis of benzo[b]furans have been reported recently. Most of them involve cyclization or cycloisomerization processes. Unquestionably, more imaginative strategies for the construction of benzo[b]furan skeleton will be established in the near future. Application of known methods to natural products or drug synthesis, on industrial scale for the synthesis of economically or medicinally important benzo[ b]furans will probably be paid attention to.