Chiral bifunctional organocatalysts for enantioselective synthesis of 3-substituted isoindolinones.

A series of chiral bifunctional organocatalysts were prepared and used for enantioselective synthesis of 3-substituted isoindolinones from 2-formylarylnitriles and malonates through aldol-cyclization rearrangement tandem reaction in excellent yields and enantioselectivites (up to 87% yield and 95% ee) without recrystallization. In this investigation, we found that chiral tertiary-amine catalysts with a urea group can afford 3-substituted isoindolinones both in higher yields (87% vs. 77%) and enantioselectivities (95% ee vs. 46% ee) than chiral bifunctional phase-transfer catalysts.

Chiral Cyclopropenimine-catalyzed Asymmetric Michael Addition of Bulky Glycine Imine to α,ß-Unsaturated Isoxazoles.

A highly efficient asymmetric Michael addition of bulky glycine imine to α,ß-unsaturated isoxazoles has been achieved by using 5 mol% of chiral cyclopropenimine as a chiral organo-superbase catalyst under mild conditions. Michael adducts were obtained in excellent yields (up to 97%) and stereoselectivities (up to >99 : 1 dr and 98% ee). A significant solvent effect was found in these chiral organosuperbase catalyzed asymmetric Michael reactions. Gram-scale preparation of Michael adducts and their transformations are realized to provide corresponding products without loss of stereoselectivities. The configurations of Michael adduct was determined by single-crystal X-ray diffraction analysis.

Bifunctional phase-transfer catalysts for synthesis of 2-oxazolidinones from isocyanates and epoxides.

A series of bifunctional phase-transfer catalysts (PTCs) were synthesized to catalyze the [3 + 2] coupling reaction of isocyanates and epoxides to afford 2-oxazolidinones in good to high yields (up to 92% yield) using PhCl as a solvent at 100 °C within 12 h. These bifunctional PTCs were easily prepared from commercially available tertiary-primary diamines and isocyanates (or isothiocyanates, mono-squaramides, respectively) in two simple steps with good modularity and demonstrated high efficiency (2.5 mol% catalyst-loading). The synergistic interaction of the quaternary ammonium salt center and hydrogen-bond donor group in the catalyst with the substrate is crucial to this atom-economic reaction.

CRISPR-Cas9 assisted functional gene editing in the mushroom Ganoderma lucidum.

The genetic manipulation of basidiomycete mushrooms is notoriously difficult and immature, and there is a lack of research reports on clustered regularly interspaced short palindromic repeat (CRISPR) based gene editing of functional genes in mushrooms. In this work, Ganoderma lucidum, a famous traditional medicinal basidiomycete mushroom, which produces a type of unique triterpenoid-anti-tumor ganoderic acids (GAs), was used, and a CRISPR/CRISPR-associated protein-9 nuclease (Cas9) editing system for functional genes of GA biosynthesis was constructed in the mushroom. As proof of concept, the effect of different gRNA constructs with endogenous u6 promoter and self-cleaving ribozyme HDV on ura3 disruption efficiency was investigated at first. The established system was applied to edit a cytochrome P450 monooxygenase (CYP450) gene cyp5150l8, which is responsible for a three-step biotransformation of lanosterol at C-26 to ganoderic acid 3-hydroxy-lanosta-8, 24-dien-26 oic acid. As a result, precisely edited cyp5150l8 disruptants were obtained after sequencing confirmation. The fermentation products of the wild type (WT) and cyp5150l8 disruptant were analyzed, and a significant decrease in the titer of four identified GAs was found in the mutant compared to WT. Another CYP gene involved in the biosynthesis of squalene-type triterpenoid 2, 3; 22, 23-squalene dioxide, cyp505d13, was also disrupted using the established CRISPR-Cas9 based gene editing platform of G. lucidum. The work will be helpful to strain molecular breeding and biotechnological applications of G. lucidum and other basidiomycete mushrooms.

BES1 is activated by EMS1-TPD1-SERK1/2-mediated signaling to control tapetum development in Arabidopsis thaliana.

BES1 and BZR1 were originally identified as two key transcription factors specifically regulating brassinosteroid (BR)-mediated gene expression. They belong to a family consisting of six members, BES1, BZR1, BEH1, BEH2, BEH3, and BEH4. bes1 and bzr1 single mutants do not exhibit any characteristic BR phenotypes, suggesting functional redundancy of these proteins. Here, by generating higher order mutants, we show that a quintuple mutant is male sterile due to defects in tapetum and microsporocyte development in anthers. Our genetic and biochemical analyses demonstrate that BES1 family members also act as downstream transcription factors in the EMS1-TPD1-SERK1/2 pathway. Ectopic expression of both TPD1 and EMS1 in bri1-116, a BR receptor null mutant, leads to the accumulation of non-phosphorylated, active BES1, similar to activation of BES1 by BRI1-BR-BAK1 signaling. These data suggest that two distinctive receptor-like kinase-mediated signaling pathways share BES1 family members as downstream transcription factors to regulate different aspects of plant development.

Tandem grinding reactions involving aldol condensation and Michael addition in sequence for synthesis of 3,4,5-trisubstituted isoxazoles.

A one-pot, base-catalyzed, tandem grinding process involving carrying out aldol condensation and Michael addition in sequence to produce 3,4,5-trisubstituted isoxazoles from 3,5-dimethyl-4-nitroisoxazole, aromatic aldehydes and activated methylene compounds has been developed. In the presence of 10 mol% of pyrrolidine, aldol condensations of 3,5-dimethyl-4-nitroisoxazole with various aromatic aldehydes were performed with 3-10 minutes of grinding to provide 5-styryl-3-methyl-4-nitroisoxazoles in good to quantitative yields without further purification. Then, Michael additions between 5-styryl-3-methyl-4-nitroisoxazoles and activated methylene compounds (including ethyl 2-nitroacetate and alkyl 2-cyanoacetates) were carried out in the presence of 10 mol% of Et3N in the same mortar with 3-5 minutes of continuous grinding to produce 3,4,5-trisubstituted isoxazoles in good to excellent yields.

Highly Efficient Michael Reactions of Nitroolefins by Grinding Means.

AIM AND OBJECTIVE: The direct ß-functionalization of trans-ß-nitroolefins by Michael reaction is regarded as an efficient way to provide precursors for ß-functional amines. However, Michael additions by grinding means with solvent-free conditons are rarely reported. We have developed facile access to ß-functional nitroalkanes by grinding means under solvent-free conditions. MATERIALS AND METHODS: From commercially available materials including ethyl 2-nitroacetate, alkyl 2-cyanoacetates and malononitrile, the grinding reactions between these above-mentioned activated methylenecompounds and various trans-ß-nitroolefins were performed at room temperature and solvent-free conditions. RESULTS: A highly efficient direct Michael reaction of nitroolefins by simple grinding means has been developed. Various trans-nitrostyrenes were easily converted into corresponding ß-functional nitroalkanes in excellent yields within 5~10 min (up to 36 examples). CONCLUSION: Herein, we have developed a simple and efficient way to ß-functional nitroalkanes through Michael reactions by grinding means. The grinding Michael reaction is fast, clean and stable and these Michael adducts could be easily converted into the other amino compounds served as building blocks in organic synthesis.

A New Class of Glucosyl Thioureas: Synthesis and Larvicidal Activities.

A novel series of glucosyl thioureas were synthesized in good overall yields (up to 37% over four steps) from d-glucose and primary amines, and their larvicidal activities toward Mythimna separata Walker were also investigated. This new class of glucosyl thioureas demonstrated low to moderate growth inhibition activity of Mythiman separata Walker, with a growth inhibitory rate of up to 47.5% at a concentration of 100.0 mg/L in acetone.

Facile access to unnatural dipeptide-alcohols based on cis-2,5-disubstituted pyrrolidines.

Well-defined unnatural dipeptide-alcohols based on a cis-2,5-disubstitued pyrrolidine backbone were synthesized from commercially available starting materials meso-diethyl-2,5-dibromoadipate, (S)-(-)-1-phenylethylamine, and phenylalaninol. The structures of these unnatural dipeptide-alcohols are supported by HRMS, 1H- and 13C-NMR spectroscopy. These unnatural dipeptide-alcohols can act as building blocks for peptidomimetics.

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides.

Enantioselective desymmetrization of meso-aziridines and meso-epoxides with various nucleophiles by organocatalysis has emerged as a cutting-edge approach in recent years. This review summarizes the origin and recent developments of enantioselective desymmetrization of meso-aziridines and meso-epoxides in the presence of organocatalysts.

Novel role of NOD2 in mediating Ca2+ signaling: evidence from NOD2-regulated podocyte TRPC6 channels in hyperhomocysteinemia.

Although hyperhomocysteinemia (hHcys) has been recognized as an important independent risk factor in the progression of end-stage renal disease and in the development of cardiovascular complications related to end-stage renal disease, the mechanisms triggering the pathogenic actions of hHcys are not yet fully understood. The present study was designed to investigate the contribution of nucleotide-binding oligomerization domain containing 2 (NOD2), an intracellular innate immunity mediator, to the development of glomerulosclerosis in hHcys. Our results showed that NOD2 deficiency ameliorated renal injury in mice with hHcys. We further discovered the novel role of NOD2 in mediating Ca(2+) signaling and found that homocysteine-induced NOD2 expression enhanced transient receptor potential cation channel 6 (TRPC6) expression and TRPC6-mediated calcium influx and currents, leading to intracellular Ca(2+) release, ultimately resulting in podocyte cytoskeleton rearrangement and apoptosis. Moreover, we found that nephrin expression was downregulated dependently by NOD2, and overexpression of nephrin attenuated homocysteine-induced TRPC6 expression in podocytes. The results add evidence to support the essential role of nephrin in mediating NOD2-induced TRPC6 expression in hHcys. In conclusion, our results for the first time establish a previously unknown function of NOD2 for the regulation of TRPC6 channels, suggesting that TRPC6-dependent Ca(2+) signaling is one of the critical signal transduction pathways that links innate immunity mediator NOD2 to podocyte injury. Pharmacological targeting of NOD2 signaling pathways at multiple levels may help design a new approach to develop therapeutic strategies for treatment of hHcys-associated end-stage renal disease.

HDAC4/5-HMGB1 signalling mediated by NADPH oxidase activity contributes to cerebral ischaemia/reperfusion injury.

Histone deacetylases (HDACs)-mediated epigenetic mechanisms play critical roles in the homeostasis of histone acetylation and gene transcription. HDAC inhibitors have displayed neuroprotective properties in animal models for various neurological diseases including Alzheimer's disease and ischaemic stroke. However, some studies have also reported that HDAC enzymes exert protective effects in several pathological conditions including ischaemic stress. The mixed results indicate the specific roles of each HDAC protein in different diseased states. However, the subtypes of HDACs associated with ischaemic stroke keep unclear. Therefore, in this study, we used an in vivo middle cerebral artery occlusion (MCAO) model and in vitro cell cultures by the model of oxygen glucose deprivation to investigate the expression patterns of HDACs and explore the roles of individual HDACs in ischaemic stroke. Our results showed that inhibition of NADPH oxidase activity ameliorated cerebral ischaemia/reperfusion (I/R) injury and among Zn(2+) -dependent HDACs, HDAC4 and HDAC5 were significantly decreased both in vivo and in vitro, which can be reversed by NADPH oxidase inhibitor apocynin. We further found that both HDAC4 and HDAC5 increased cell viability through inhibition of HMGB1, a central mediator of tissue damage following acute injury, expression and release in PC12 cells. Our results for the first time provide evidence that NADPH oxidase-mediated HDAC4 and HDAC5 expression contributes to cerebral ischaemia injury via HMGB1 signalling pathway, suggesting that it is important to elucidate the role of individual HDACs within the brain, and the development of HDAC inhibitors with improved specificity is required to develop effective therapeutic strategies to treat stroke.

One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes.

A series of chiral 10-heteroazatriquinanes were synthesized from enantiopure asymmetric cis-2,5-disubstituted pyrrolidines through a one-pot tandem cyclization procedure. The structures and configurations of these new chiral 10-heteroazatriquinanes are confirmed by X-ray single-crystal diffraction analysis.

Hair fiber as a nanoreactor in controlled synthesis of fluorescent gold nanoparticles.

The synthesis and detailed characterization of gold nanoparticles (AuNPs) inside human hair has been achieved by treatment of hair with HAuCl(4) in alkaline medium. The AuNPs, which show a strong red fluorescence under blue light, are generated inside the fiber and are arranged in the cortex in a remarkably regular pattern of whorls based on concentric circles, like a fingerprint. It opens an area of genuine nanocomposites with novel properties due to AuNPs inside the hair shaft.

Efficient synthesis of unnatural dipeptides based on cis-2,5-disubstituted pyrrolidine.

The well-defined unnatural dipeptides based on cis-2,5-disubstituted pyrrolidine backbone were synthesized from commercially available starting materials meso-diethyl-2,5-dibromoadipate, (S)-(-)-1-phenylethylamine, and phenylalanine. The configurations of all the chiral centers in these unnatural dipeptides are confirmed by X-ray crystal diffraction analysis.

1-(4-Amino-3,5-dichloro-phen-yl)ethanol.

The asymmetric unit of the title compound, C(8)H(9)Cl(2)NO, contains two crystallographically independent mol-ecules which are connected via an N-H⋯O hydrogen bond . There is aromatic π-π stacking in the crystal, with a centroid-centroid distance between benzene rings of 3.48 (2)Å. The crystal packing is stabilized by intermolecular hydrogen bonds.

Ethyl 4-benzamido-5-phenyl-4H-1,2,4-triazole-3-carboxyl-ate monohydrate.

In the title compound, C(18)H(16)N(4)O(3)·H(2)O, the dihedral angles between the triazole ring and the phenyl rings are 84.8 (4) and and 39.8 (4)°. The phenyl rings make a dihedral angle of 84.5 (9)°. In the crystal, the molecules are linked by N-H⋯O and O-H⋯N hydrogen bonds. An intra-molecular O⋯N inter-action also occurs [2.827 (3) Å].

(S)-1-Ferrocenyl-3-hy-droxy-3-phenyl-propan-1-one.

In the title compound, [Fe(C(5)H(5))(C(14)H(13)O(2))], the dihedral angle between the phenyl ring and the unsubstituted cyclo-petadienyl ring is 85.0 (2)°while that between the phenyl ring and the substituted cyclo-petadienyl ring is 83.6 (2)°. The dihedral angle between the two cyclo-penta-1,3-diene rings of the ferrocene unit is 2.2 (2)°. The mol-ecules are stabilized by inter-molecular O-H⋯O hydrogen-bonding inter-action within the crystal lattice.

2,2-Dichloro-1-(4-methyl-phen-yl)ethanone.

The mol-ecule of the title compound, C(9)H(8)Cl(2)O, is almost planar: the dihedral angle between the benzene ring and the plane defined by the carbonyl O and ethane C atoms is 15.5 (2)°. The crystal packing is stabilized by inter-molecular C-H⋯O hydrogen bonds.

Synthesis and anti-HCV activity of a new 2'-deoxy-2'-fluoro-2'-C-methyl nucleoside analogue.

2'-Deoxy-2'-fluoro-2'-C-methyl nucleoside analogue 4 was designed and synthesized. Initial biological studies indicated that this compound showed promising activity against HCV replication.