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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.

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 palladium-catalyzed oxidative cross-coupling of vinyl boronic acids and cyclic α-diazocarbonyl compounds has been reported. The reaction constitutes an efficient method for the synthesis of 1,3-diene compounds bearing a ring structure. Mechanistically, the reaction involves migratory insertion of palladium carbene as the key step.

The first total synthesis of dilignan Boehmenan has been achieved. A biomimetic oxidative coupling of the ferulic acid methyl ester in the presence of silver oxide is the crucial step in the synthesis sequence, generating the dihydrobenzofuran skeleton. Hydroxyl group was protected with DHP and reducted with LiAlH 4 to afford the intermediate diol. The diol was condensated with the derivative of ferulic acid, then removed the protecting groups, to get Boehmenan. Meanwhile, a study on the ring-opening reaction of the intermediate dihydrobenzofuran neolignan under base conditions was described.

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.

A readily available chiral camphor-derived auxiliary was synthesised through a highly efficient and short general route. The Darzens reaction of the auxiliary with aldehydes in the presence of base gave glycidic esters with almost complete diastereocontrol and high yield.

The present study describes the performance of the HZSM-5 zeolite catalyst modified by Cu, Zn, Ga, La, P, Ag, and other ions for the conversion of methanol to aromatics in a fixed-bed reactor, and the influences of the system pressure and temperature on methanol aromatization are in discussion. The results show that the optimum single ion for the modification of catalyst was Zn or Cu. The optimum combined ions were Zn and Ga. The yield of aromatics could reach up to 66.6% on the catalyst modified with Ga2% and Zn10%.

A convenient method for the synthesis of lignanamide Cannabisin G, starting from the vanillin, was developed. The convergent synthesis was based on the Stobbe reaction as C-C bond-forming steps to give the skeleton of lignan, which was condensed with a derivative of tyramine to obtain synthetic Cannabisin G for the first time.

The total synthesis of threo-(±)-9,9-dibenzoylsecoisolariciresinol and its isomer based on two Stobbe reactions as C–C bond-forming steps used a protected vanillin and diethyl; succinate to give the skeleton of lignan, followed by reduction to afford threo- and meso-(±)-secoisolariciresinol Both were treated with benzoyl chloride to obtain the natural product threo-(±)-9,9-dibenzoylsecoisolariciresinol and Its isomer meso-(±)-9,9-dibenzoylsecoisolariciresinol for the first time.

Benzimidazole ring system is a useful nucleus in medicinal chemistry and is found in many biologically active compounds. An efficient approach for the synthesis of 1,2-bisubstituted benzimidazoles is presented in this article, and the mechanism of the condensation from 2-[(2-aminophenylimino)phenylmethyl]-4-bromophenol, using piperdine or acetic acid as catalyst, is studied. 1,3-Shift of negative hydrogen ion is the key step for this rearrangement reaction, and the influences of catalyst, temperature, substrate, and solvent are also investigated. J. Heterocyclic Chem., 2011.

A convenient method for the synthesis of sesquilignan threo- and erythro-(±)-divanillyltetrahydrofuran ferulate is described. The synthesis was based on a unified synthetic strategy involving two Stobbe condensations to give the skeleton of lignan, and then reduction reaction to form meso- and threo-(±)-secoisolanciresinol. meso- and threo-(±)-secoisolanciresinol were separated by flash column chromatography, followed by intramolecular reaction with TsCl to afford the key intermediate meso- or threo-(±)-shonanin, then condensation with ferulaic acid to obtain sesquilignan threo- or its analogue erythro-(±)-divanillyltetrahydrofuran ferulate.

Full details of the total syntheses of erythro-nordihydroguaiaretic acid, threo-(-)-saururenin and their analogues are presented. The syntheses were based on a unified synthetic strategy involving the Stobbe Reaction, alkylation to construct the skeleton of lignans and resolution of the threo- and erythro-isomers. The syntheses were achieved in eight to nine steps from simple aromatic precursors, and by this route 13 lignans were obtained. Among the synthesized lignans, seven lignans were natural products; moreover three of the seven natural products were synthesized for the first time. The effect of 13 lignans was examined on HIV Tat transactivation in human epithelial cells, HSV-1 gene and human leukemic, liver, prostate, stomach and breast cancer cell. Bioactivity results indicated that one product showed activity against the HIV gene and five compounds exhibited anti-HSV activity.

An efficient synthesis of dibenzylbutyrolactone lignans and their analogues has been developed. Based on a Stobbe condensation of piperonal or veratraldehyde with diethylsuccinate and alkylation with 3,4-methylenedioxybenzyl bromide to give the skeleton of the lignan. The (±)-diacid was resolved with quinine and the functional groups were transformed to obtain three benzylbutyrolactone lignans and seven analogues. Four natural lignans were prepared by this method, and five lignans were synthesised for the first time. The synthesised compounds were evaluated for anti-HIV, anti-HSV, and anti-tumour activities. Results showed that the dibenzylbutyrolactone lignans and their analogues were inactive against HIV Tat transactivation and HSV-1 in vitro, but some compounds displayed significant activity against MDA-MB-435 human breast cancer cell.

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.

An enantioselective total synthesis of chiral daphneticin and its regioisomer is reported for the first time.

The asymmetric synthesis of the natural neolignan (1R,2S)-2-(4′-allyl-2′,6′-dimethoxyphenoxyl)-1-(4″-hydroxy-3″,5″-dimethoxyphenyl)propan-1-ol based on an asymmetric dihydroxylation as a key reaction using AD-mix-β to preparing the chiral threo-(1R,2R)-glycerol. The reaction, threo-alcohols were inverted by an SN2 reaction into erythro-(1R,2S)-isomers.

A synthesis of the tetrahydrofuran lignan (±)-agastinol, starting from the cheap Vanillin, has been developed based on Stobbe reaction with diethyl succinate to give the skeleton of lignan, which was then reduced to afford meso- and threo-(±)-secoisolanciresinol. threo-(±)-Secoisolanciresinol was treated with DDQ in acetic acid to give the 2-aryl tetrahydrofuran lignan, and which was then condensed with ferulic acid to give (±)-agastinol for the first time.

This method has good functional group tolerance and provides a novel alternative for the efficient synthesis of highly substituted furan derivatives.

A readily available chiral camphor-derived auxiliary was synthesised through a highly efficient and short general route. The Darzens reaction of the auxiliary with aldehydes in the presence of base...

A facile synthesis of the title natural neolignan (VI) is developed involving an asymmetric Sharpless dihydroxylation [(III)] and a Mitsunobu reaction as the key steps.

Benzimidazole ring system is a useful nucleus in medicinal chemistry and is found in many biologically active compounds. An efficient approach for the synthesis of 1,2-bisubstituted benzimidazoles is presented in this article, and the mechanism of the condensation from 2-[(2-aminophenylimino)phenylmethyl]-4-bromophenol, using piperdine or acetic acid as catalyst, is studied. 1,3-Shift of negative hydrogen ion is the key step for this rearrangement reaction, and the influences of catalyst, temperature, substrate, and solvent are also investigated. J. Heterocyclic Chem., 2011.

Full details of the asymmetric total synthesis of erythro-8-O-4′-neolignan, machilin C, and its analogue perseal A are reported. The synthesis was involved in the Sharpless dihydroxylation reaction that occurred with excellent asymmetric induction, and the Mitsunobu reaction which occurred with inversion of the absolute configuration from the threo to the erythro isomer. The synthesis was achieved from simple vanillin in eight to twelve steps.

A biotransformation process was developed for the production of (S)-ketoprofen by enantioselective hydrolysis of racemic ketoprofen ester using the mutant Trichosporon laibacchii strain CBS 5791. A satisfactory result was obtained, in which the E was 82.5, with an ee of 0.94 and a conversion of 0.47 under the optimum hydrolysis conditions [E is enantiomeric ratio, E=ln[1-X(1+ee)]/ln[1-X(1-ee)]; ee is enantiomeric excess, ee=(CS-CR)/(CS+CR): temperature of hydrolysis was 23 degrees C]. The medium used in biotransformation was a mixture of growth broth and biotransformation broth at a ratio of 1:9, the concentration of Tween 80 was 15 g/l, the time of hydrolysis, 72 h. These results are promising for further scale-up. Tween 80 significantly improved lipase enantioselectivity and activity at the optimum concentration.

A new methodology for the synthesis of the erythro -8- O -4’-neolignan Machilin C based on the Sharpless asymmetric dihydroxylation reaction and the Mitsunobu reaction as two key steps is described.

In the title compound, C19H15BrN2O, the dihedral angles formed by the imide group and the three benzene rings are 56.5 (2), 6.2 (4) and 55.7 (1)°. The mol­ecular structure and packing are stabilized by O—H⋯N, N—H⋯O and N—H⋯N inter­molecular hydrogen-bond inter­actions and C—H⋯π inter­actions.