Enantioselective Medium-Ring Lactone Synthesis through an NHC-Catalyzed Intramolecular Desymmetrization of Prochiral 1,3-Diols

A highly enantioselective intramolecular annulation reaction of 1,3-diols catalyzed by a triazolium N-heterocyclic carbene (NHC) precatalyst is disclosed, affording the corresponding medium-sized lactones in moderate to good yields with high enantioselectivities. It is worth noting that this compatible catalytic system has been successfully applied to assemble a broad range of chiral medium-sized lactones, including ones with eight-, nine-, ten-, eleven-, and twelve-membered rings

α‑Fluoroallenoate Synthesis via N‑Heterocyclic Carbene-Catalyzed Fluorination Reaction of Alkynals

The first catalytic α-fluoroallenoate synthesis is described. With a suitable combination of N-heterocyclic carbene precatalyst, base, and fluorine reagent, the reaction proceeded smoothly to yield a wide range of α-fluoroallenoates with excellent chemoselectivity. These substituted α-fluorinated allenoates have been synthesized for the first time, and they are versatile synthetic intermediates toward other useful fluorine-containing building blocks

Photocatalytic C–S Bond Formation Using <i>N</i>‑Thiophthalimide and <i>N-</i>Perthiophthalimide Derivatives

Unsymmetric disulfides are shown to be accessed directly from carboxylic acids or trifluoroborate salts by using N-perthiophthalimide derivatives (Harpp reagents) under photoredox catalysis. While this would appear to involve homolytic substitution of alkyl radicals on the Harpp reagents, the formation of the high-energy phthalimidyl radical renders this reaction prohibitively endergonic. Instead, computations and experiments suggest that the Harpp reagents are reduced in situ to form perthiyl radicals that dimerize to tetrasulfides (RSSSSR), which have previously been demonstrated to undergo radical substitution to give disulfides. Given these results, examples of previously reported radical sulfurations using N-thiophthalimide reagents under photoredox catalysis were investigated. Our results suggest that these reactions are likely to proceed via in situ formation of the corresponding disulfide as the sulfuration reagent rather than direct substitution on the N-thiophthalimide. The implications of these findings for the use of phthalimide (and related) derivatives in photoredox-catalyzed reactions are discussed

Chemoselective N‑Heterocyclic Carbene-Catalyzed Cascade of Enals with Nitroalkenes

An unprecedented N-heterocyclic carbene catalyzed chemoselective and enantioselective cascade reaction of enals with nitroalkenes has been developed. A wide range of enantioenriched dihydrocoumarins has been prepared, and the reaction goes through an enolate intermediate generated under a catalytic process

Cooperative Palladium/Proline-Catalyzed Direct α‑Allylic Alkylation of Ketones with Alkynes

The cooperative palladium/l-proline-catalyzed direct α-allylic alkylation of ketones with alkynes is achieved. This reaction exhibits high atom economy since a leaving group is not liberated and a stoichiometric amount of extra oxidant is not needed. A broad range of functional groups are tolerated, and the reaction scope could be further expanded to aldehydes

Palladium-Catalyzed Dearomative Allylic Alkylation of Indoles with Alkynes To Synthesize Indolenines with C3-Quarternary Centers

A palladium-catalyzed dearomative allylic alkylation of indoles with alkynes to construct indolenines with C3-quarternary centers was reported. The in situ formed arylallene intermediate omitted the need to install leaving groups on the allylic compounds and employ extra oxidants to oxidize the allylic C–H bonds. The reaction exhibited good functional group tolerance and high atom economy. Moreover, the reaction was further expanded to synthesize pyrroloindolines and furanoindolines

Microbial Distribution in a Hydrothermal Plume of the Southwest Indian Ridge

<p>Hydrothermal plumes are widely distributed throughout the global spreading ridges, yet few of them are microbiologically explored. The ultraslow-spreading ridges, recently recognized as a unique, new class of mid-ocean-ridge system, have provided surprises and new insights in hydrothermal system research. A suite of water column samples including both hydrothermal plume samples and ambient seawater were collected at different depths from the ultraslow-spreading Southwest Indian Ridge (SWIR) in 2010. We use molecular approaches such as clone libraries, denaturing gradient gel electrophoresis (DGGE) and quantitative PCR to determine microbial community compositions and their spatial variability within the hydrothermal plume and seawater. Phylogenetic analysis showed that plume samples were mainly dominated by members of <i>α-Proteobacteria</i> and <i>γ-Proteobacteria</i> and members of marine group I group within the <i>Crenarchaeota</i>. Within the hydrothermal plume, archaeal populations were spatially homogeneous, while bacterial compositions were heterogeneous and remarkably distinct at different depths. Moreover, several lineages, closely related to known Mn(II) oxidizers were found to be abundant and even predominant within the plume bacterial communities. DGGE band patterns showed that there was no significant difference in microbial compositions between the samples of hydrothermal plume and ambient seawater. Taken together, we inferred that microbial communities in the SWIR hydrothermal plumes were sourced from ambient seawater rather than from seafloor vent-derived niches. This is the first report on the characteristics of microbial community structures in hydrothermal plume and ambient seawater in the Southwest Indian Ridge.</p

Additional file 1 of BinaRena: a dedicated interactive platform for human-guided exploration and binning of metagenomes

Additional file 1: Fig. S1. Correlation between completeness (A) and redundancy (contamination) (B) values calculated by BinaRena and CheckM. A total of 596 bins recovered by MaxBin and MetaBAT from the MAQ dataset were evaluated. The CheckM marker gene set for domain Bacteria was used, which contains 104 genes arranged in 58 sets. The regression line (black) is plotted in each panel. The Pearson’s correlation coefficient (r) and its p-value are marked under the plot. Fig. S2. Sulfotelmatobacter MAGs identified by three automatic binners. Scatter plots were defined by t-SNE on k-mer (k = 6) frequencies. Marker size (radius) is proportional to contig length. Marker opacity is proportional to the cube root of contig coverage in location 3 at depth of 20cm. A. MaxBin’s result. B, C. MetaBAT’s results. D, E. DASTool’s results which are both subsets of MaxBin results. D came from a bin with high redundancy (contamination) (40.89%) and only classified to the family level (Koribacteraceae) and E is a subset of panel A. F. Multi-panel scatter plot representing contig coverage across metagenomes for curated Sulfotelmatobacter MAG. Gray circles represent contigs without dsrAB, while the red circle represents the potentially misplaced contigs with dsrAB. Fig. S3. Various views of the TD metagenome #76. Three dimensionality reduction methods, PCA, t-SNE, and UMAP, were applied to k-mer frequency profiles with k = 4, 5, and 6. In addition, the coverage (log) was plotted against GC content and contig length (log). Marker size (radius) is proportional to the cube root of contig length. Except for the last two plots (in which contig coverage is the y-axis), marker opacity is proportional to the square root of contig coverage. Colors are assigned to the top nine most abundant families. The color codes are identical to that of Fig. 3A, B. Fig. S4. Comparison of an Escherichia MAG identified by three automatic binners. Scatter plots were defined by t-SNE on k-mer (k = 6) frequencies. Marker size (radius) is proportional to the cube root of contig length. Marker opacity is proportional to the square root of contig coverage. A. MaxBin’s result (see also Fig. 3G), which has the highest consistency with the manually identified MAG (Fig. 3F). B. MetaBAT’s result (also DASTool’s primary result), which contains a proportion of the Escherichia contigs plus a separate contig cluster assigned to genus Faecalibacterium (dashed circle). C. DASTool’s secondary result (equivalent to the MaxBin bin excluding the MetaBAT bin). Fig. S5. Recovery of a pathogenic Escherichia coli MAG from TD sample #50076 (19.82 Gbp raw reads, 9,816 contigs totaling 62.2 Mbp), which contains multiple E. coli strains. Scatter plot was defined by t-SNE on k-mer (k = 6) frequencies. Marker size (radius) is proportional to the cube root of contig length. Marker opacity is proportional to the cube root of contig coverage. Colors were assigned to the top 14 most abundant genera in the sample. A. View of the entire assembly. A cluster of contigs mainly assigned to Escherichia was selected (dashed polygon). B. The selected cluster of contigs. Its coverage profile exhibits a multi-modal pattern (inset of A). Therefore, the top five out of 20 bins of the histogram were retained. C. The retained contigs, which represent a putative E. coli MAG. Table S1. Comparison of functionality of BinaRena and Elviz. Table S2. Metrics of contig clusters / bins in TD sample #76 calculated by BinaRena. Table S3. Metrics of contig clusters / bins in TD sample #50076 calculated by BinaRena

Redox-Neutral Atom-Economic Pd(0)-Catalyzed Dearomatization of β‑Naphthols with Alkynes toward Naphthalenones

A dearomative coupling of β-naphthols with alkynes via Pd hydride catalysis has been developed. This redox-neutral strategy provides a straightforward platform to access diverse naphthalenones bearing congested quarternary stereocenters with excellent atom and step economy since no leaving groups are needed to preinstall on the allylic reagents. The overall utility of this protocol is exemplified by broad functional group compatibility and gram-scale capacity

Odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between the different types of night shift work and abdominal obesity in 3,871 Chinese workers.

<p>Odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between the different types of night shift work and abdominal obesity in 3,871 Chinese workers.</p