RESUMO
The construction of multiple continuous fully substituted carbon centers, which serve as unique structural motif in natural products, is a challenging topic in organic synthesis. Herein, we report a hydrated [3+2] cyclotelomerization of butafulvenes to create contiguous fully substituted carbon backbone. In the presence of scandium triflate, all-carbon skeleton with spiro fused tricyclic ring can be constructed in high diastereoselectivity by utilizing butafulvene as the synthon. Mechanistic studies suggest that this atom-economic reaction probably proceeds through a synergistic process containing butafulvenes dimerization and nucleophilic attack by water. In addition, the tricyclic product can undergo a series of synthetic derivatizations, which highlights the potential applications of this strategy. The recyclability of Sc(OTf)3 has also been demonstrated to show its robust performance in this hydrated cyclotelomerization.
RESUMO
The recent surge in the applications of deuterated drug candidates has rendered an urgent need for diverse deuterium labeling techniques. Herein, an efficient Rh-catalyzed deuterated Tsuji-Wilkinson decarbonylation of naturally available aldehydes with D2O is developed. In this reaction, D2O not only acts as a deuterated reagent and solvent but also promotes Rh-catalyzed decarbonylation. In addition, decarbonylative strategies for the synthesis of terminal monodeuterated alkenes from α,ß-unsaturated aldehydes are within reach.
Assuntos
Ródio , Aldeídos , Alcenos , Catálise , Óxido de DeutérioRESUMO
An efficient method for the synthesis of alkyl indium reagent by means of an iodine-catalyzed direct indium insertion into alkyl iodide in THF is reported. The thus-generated alkyl indium reagents effectively underwent Pd-catalyzed cross-coupling reactions with various aryl halides, exhibiting good compatibility to a variety of sensitive functional groups. By replacing THF with DMA and using 0.75 equiv of iodine, less reactive alkyl bromide could be used as substrate for indium insertion with equal ease.
RESUMO
Carbon dioxide is commonly used as one of the significant environmental factors to control pileus expansion during mushroom cultivation. However, the pileus expansion mechanism related to CO2 is still unknown. In this study, the young fruiting bodies of a popular commercial mushroom Flammulina filiformis were cultivated under different CO2 concentrations. In comparison to the low CO2 concentration (0.05%), the pileus expansion rates were significantly lower under a high CO2 concentration (5%). Transcriptome data showed that the up-regulated genes enriched in high CO2 concentration treatments mainly associated with metabolism processes indicated that the cell metabolism processes were active under high CO2 conditions. However, the gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with cell division processes contained down-regulated genes at both 12 h and 36 h under a high concentration of CO2. Transcriptome and qRT-PCR analyses demonstrated that a high CO2 concentration had an adverse effect on gene expression of the ubiquitin-proteasome system and cell cycle-yeast pathway, which may decrease the cell division ability and exhibit an inhibitory effect on early pileus expansion. Our research reveals the molecular mechanism of inhibition effects on early pileus expansion by elevated CO2, which could provide a theoretical basis for a CO2 management strategy in mushroom cultivation.
Assuntos
Dióxido de Carbono/farmacologia , Divisão Celular , Flammulina/genética , Carpóforos/genética , Proteínas Fúngicas/genética , Transcriptoma/efeitos dos fármacos , Biologia Computacional , Flammulina/efeitos dos fármacos , Flammulina/crescimento & desenvolvimento , Carpóforos/efeitos dos fármacos , Carpóforos/crescimento & desenvolvimento , Perfilação da Expressão GênicaRESUMO
Small GTPases play important roles in the growth, development and environmental responses of eukaryotes. Based on the genomic sequence of the straw mushroom Volvariella volvacea, 44 small GTPases were identified. A clustering analysis using human small GTPases as the references revealed that V. volvacea small GTPases can be grouped into five families: nine are in the Ras family, 10 are in the Rho family, 15 are in the Rab family, one is in the Ran family and nine are in the Arf family. The transcription of vvran1 was up-regulated upon hydrogen peroxide (H2O2) stress, and could be repressed by diphenyleneiodonium chloride (DPI), a NADPH oxidase-specific inhibitor. The number of vvran1 transcripts also increased upon cold stress. Diphenyleneiodonium chloride, but not the superoxide dismutase (SOD) inhibitor diethy dithiocarbamate (DDC), could suppress the up-regulation of vvran1 gene expression to cold stress. These results combined with the high correlations between gene expression and superoxide anion (O2(-)) generation indicated that vvran1 could be one of the candidate genes in the downstream of O2(-) mediated pathways that are generated by NADPH oxidase under low temperature and oxidative stresses.
Assuntos
Peróxido de Hidrogênio/farmacologia , Proteínas Monoméricas de Ligação ao GTP/genética , Estresse Fisiológico , Volvariella/enzimologia , Temperatura Baixa , Proteínas Fúngicas/genética , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Humanos , Família Multigênica , Oniocompostos/farmacologia , Filogenia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Volvariella/genética , Proteína ran de Ligação ao GTP/genéticaRESUMO
Homocitrate synthase (EC 2.3.3.14) regulates the first step of fungal lysine biosynthesis. The gene encoding homocitrate synthase was identified in whole genomic sequencing of Flammulina velutipes and contains seven introns. The homocitrate synthase gene of F. velutipes strain W23 (Fvhcs) is 1780 bp in length and encodes a 464 amino acid protein with a predicted molecular weight 50.7 kDa. Phylogenetic analysis of Fvhcs and other homocitrate synthase proteins from diverse fungi produced a topology congruent with the current best estimate of organismal phylogeny. Analysis of protein domains by InterProScan and a motif search found that Fvhcs gene encodes homocitrate synthase protein conserved across Agaricomycotina. In addition, we sequenced the transcriptome of different developmental stages and structures of the fruiting body to analyze the expression levels of the Fvhcs gene. The data showed a correlation between Fvhcs gene expression and lysine values in different developmental stages and structures of F. velutipes.
Assuntos
Flammulina/química , Flammulina/enzimologia , Regulação Fúngica da Expressão Gênica , Lisina/análise , Oxo-Ácido-Liases/biossíntese , Análise por Conglomerados , DNA Fúngico/química , DNA Fúngico/genética , Flammulina/genética , Flammulina/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Genoma Fúngico , Íntrons , Peso Molecular , Oxo-Ácido-Liases/química , Oxo-Ácido-Liases/genética , Filogenia , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
Developing efficient strategies to realize divergent arylation of dienes has been a long-standing synthetic challenge. Herein, a nickel catalyzed divergent Mizoroki-Heck reaction of 1,3-dienes has been demonstrated through the regulation of ligands and additives. In the presence of Mn/NEt3, the Mizoroki-Heck reaction of dienes delivers linear products under Ni(dppe)Cl2 catalysis in high regio- and stereoselectivities. With the help of catalytic amount of organoboron and NaF, the use of bulky ligand IPr diverts the selectivity from linear products to branched products. Highly aryl-substituted compounds can be transformed from dispersive Mizoroki-Heck products programmatically. Preliminary experimental studies are carried out to elucidate the role of additives.
RESUMO
Metallocenes are privileged backbones in the fields of synthetic chemistry, catalysis, polymer science, etc. Direct C-H functionalization is undoubtedly the simplest approach for tuning the properties of metallocenes. However, owing to the presence of multiple identical C(sp2 )-H sites, this protocol often suffers from low reactivity and selectivity issues, especially for the regioselective synthesis of 1,3-difunctionalized metallocenes. Herein, an efficient iridium-catalyzed meta-selective C-H borylation of metallocenes is reported. With no need of preinstalled directing groups, this approach enables a rapid synthesis of various boronic esters based on benzoferrocenes, ferrocenes, ruthenocene, and related half sandwich complex. A broad range of electron-deficient and -rich functional groups are all compatible with the process. Notably, C-H borylation of benzoferrocenes takes place exclusively at the benzene ring, which is likely ascribed to the shielding effect of pentamethylcyclopentadiene. The synthetic utility is further demonstrated by easy scalability to gram quantities, the conversion of boron to heteroatoms including N3 , SePh, and OAc, as well as diverse cross-coupling reactions.
RESUMO
The mitochondrial intermediate peptidase (MIP) gene is conserved in fungi. It is linked closely with the mating-type A (mtA) gene. In this study, a fragment of the MIP gene in Volvariella volvacea (Bull. ex Fr.) Singer was first cloned by homologue-based cloning technology. Subsequently, the entire MIP DNA sequence (PYd21-MIP) was obtained after the fragment was compared with the genomic data through BLAST analysis. The PYd21-MIP sequence appeared to be homologous with the MIP gene in other fungi. Phylogenetic analysis of PYd21-MIP and other MIP sequences from diverse fungi agreed with the current organism phylogeny. Analysis of protein domains by InterProScan software and motif searching demonstrated that PYd21-MIP encodes a homologous MIP protein. These data support the hypothesis that the PYd21-MIP protein is a Hog-MIP protein homologue from V. volvacea.
Assuntos
Proteínas Fúngicas/genética , Genes Fúngicos Tipo Acasalamento , Metaloendopeptidases/genética , Volvariella/genética , China , Clonagem Molecular , DNA Fúngico/genética , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Volvariella/químicaRESUMO
Butafulvene is a constitutional isomer of benzene, comprising a cyclobutene skeleton bearing two exocyclic conjugated methylene units. As a result of the intrinsic high strain energy and anti-aromaticity, the preparation of butafulvene compounds has been a fundamental issue for the development of butafulvene chemistry. Here an efficient palladium-catalysed coupling protocol involving propargylic compounds has been developed, providing a solid and versatile strategy for the rapid assembly of symmetric butafulvene derivatives. Based on mechanistic studies, two complementary mechanisms, both involving palladium catalysis, have been confirmed. With the mechanism unveiled, the synthesis of non-symmetric butafulvenes has also been achieved. Advantages of this strategy include tolerance to a wide range of propargylic molecules, mild reaction conditions, simple catalytic systems and easy scalability. The synthetic potential of the products as platform molecules for cyclobutene derivatives has also been demonstrated.
Assuntos
Benzeno , Paládio , Catálise , Paládio/químicaRESUMO
Through the oxidative addition of cobalt into the N-C(O) bond of phthalimide and the subsequent decarbonylation, we describe an efficient cobalt-catalyzed intermolecular decarbonylative carboamidation of alkynes. High regioselectivities have been achieved for unsymmetrical alkynes (including aryl-alkyl or aryl-aryl) to deliver polysubstituted isoquinolones. To facilitate step economy, a three-component decarbonylative carboamidation of alkynes with phthalic anhydrides and amines has been demonstrated using the current cobalt catalysis.
RESUMO
A rhodium-catalyzed asymmetric allylic alkylation of pyrazol-5-ones with internal alkynes is illustrated. In the presence of a chiral rhodium-hydride catalyst, functionalized heterocyclic products bearing an all-carbon quaternary stereogenic center were obtained in high yields with satisfactory enantioselectivities. This protocol also features good regiocontrol and a high atom economy without stoichiometric by-product formation.
RESUMO
An efficient method for the preparation of alkyl indium reagents by using unactivated and cheap alkyl chlorides as substrates in the presence of indium and LiI was developed. The thus-formed alkyl indium species effectively underwent palladium-catalyzed cross-coupling reactions with aryl halides with wide functional group tolerance.