Search

Leoligin, a tetrahydrofuran lignan isolated from the root of the edelweiss plant, was synthesised from veratraldehyde (2 mol), diethyl succinate and 2-methyl-(Z)-2-butenoic acid. Initially, veratraldehyde and diethyl succinate underwent a Stobbe condensation to yield a C6-C5 acid which, after esterification, was condensed with a second molecule of veratraldehyde to generate a 2,3,4-trisubsituted γ-butyrolactone intermediate. Two reduction steps yielded a triol, which was ring-closed with tosyl chloride to form a hydroxymethyl-tetrahydrofuran, esterification of which with 2-methyl-(Z)-2-butenoic acid generated leoligin.

The first total synthesis of the dihydrobenzofuran neolignan quiquesetinerviusin A and its related structure have been described. Phenolic coupling is the key step to constructing the dihydrobenzofuran skeleton with vanillin as the raw material. The hydroxyl group was protected with dihydropyran (DHP) and the ester group was reduced with diisobutylaluminium hydride (DIBAL-H) in order to obtain the crucial intermediate diol, which was then condensed with an acid ligand to give the desired compounds following removal of the protecting groups.

Supplemental material, Supplement for First total synthesis of mariamide A by Yamu Xia, Chenglong Chen, Mengying Li, Weizeng Zhou, Shuyu Sun, Shanpeng Chu and Hui Wang in Journal of Chemical Research

Bismuth-rich oxyhalides (BixOyXz; X = Cl, Br and I) with optimized morphologies and structures have exhibited prominent photocatalytic activity for the removal of some antibacterials. So far, the antibacterials that have been efficiently degraded by BixOyXz belong to tetracycline, fluoroquinolone, sulfonamide, metronidazole and chloramphenicol. In this review, degradation mechanisms are summarized based on the significant effect of optimized morphologies and adjusted structures on the production and utilization rate of photogenerated carriers. Corresponding improvements of specific surface area, porosity and surface affinity are underlined. Constructions of binary and ternary heterostructures on the basis of 1D, 2D and 3D BixOyXz nanostructures are highlighted. Beneficial intimate interfaces, surface defects, band structure and facet exposure are emphasized. Expanding target pollutant to other categories of antibacterials and further improving photocatalytic activities of BixOyXz can pave the way for treating real wastewater containing antibacterials residues. In order to assess the practicability of BixOyXz, we need to pay great attention to the essentials of antibacterials composition, water matrix, reaction environment and extension of light-response range. Mixture solutions of several antibacterials with the ratio similar to the formulation in practically treating infections might be the preferred target pollutants in future research. We hope this review will be helpful for scientific community to employ BixOyXz photocatalysts with competitive activities for removing antibacterials residues in aqueous environments.

A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)–C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.

(E,E)-N,N-Dityramin-4,4′-dihydroxy-3,5′-dimethoxy-β,3′-bicinnamamide, a lignanamide isolated from Aptenia cordifolia, was synthesised from vanillin and tyramine. The key 8-5′-neolignan intermediate diacid was formed efficiently using oxidative coupling of the ferulic acid derivatives and the ring-opening reaction of a dihydrobenzofuran.

Cannabisin B, a naturally occurring lignanamide, has been synthesised for the first time in 15% overall yield. The convergent synthesis is based on the Stobbe reaction and Friedel–Crafts alkylation reaction as the C–C bond-forming steps to afford the skeleton of the lignanamide which was then condensed with 4-methoxyphenethylamine to obtain Cannabisin B.

2H-Chromene is an important structural motif that exists in natural products and non-natural compounds possessing interesting biological activities. In this investigation, a highly efficient approach toward 2H-chromenes has been developed based on palladium-catalyzed coupling of N-tosylhydrazones and β-bromostyrenes. The mechanism of this reaction is proposed that involves the formation of vinyl palladium by carbene migratory insertion and the intramolecular nucleophilic substitution.

A novel approach to 1,3-dienes having one double bond in a carbocyclic or oxacyclic ring by Pd-catalyzed coupling of α-diazoketones and lactones with vinyl boronic acids is presented.