Design and Synthesis of C4-Symmetric Axially Chiral ß-Aryl Porphyrins and Application for Supporting Ir(III)-Catalyzed Enantioselective C-H Alkylation.

A hitherto unknown class of C4-symmetric Caryl-Cß (C3, C8, C13, C18) axially chiral porphyrins has been synthesized and the application of their iridium (Ir) complexes in catalytic asymmetric C(sp3)-H functionalization is documented. Cyclotetramerization of enantioenriched axially chiral 2-hydroxymethyl-3-naphthyl pyrroles under mild acidic conditions affords, after oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the C4-symmetric α,α,α,α-atropenantiomer as an only isolable diastereomer. Both regioisomeric Ir(Por*)(CO)(Cl) complexes catalyze the carbene C-H insertion reaction affording the same enantiomer, albeit with slight difference in enantioselectivity. With the optimum Ir-complex 3 e, the 2-substituted arylacetic acid derivatives were generated from diazo compounds and cyclohexadiene in excellent yields and enantioselectivities.

Rhodium-Catalyzed Tandem Asymmetric Allylic Decarboxylative Addition and Cyclization of Vinylethylene Carbonates with N-Nosylimines.

A enantioselective tandem transformation, concerning asymmetric allylic decarboxylative addition and cyclization of N-nosylimines with vinylethylene carbonates (VECs), in the presence of [Rh(C2H4)2Cl]2, chiral sulfoxide-N-olefin tridentate ligand has been developed. The reaction of VECs with various substituted N-nosylimines proceeded smoothly under mild conditions, providing highly functionalized oxazolidine frameworks in good to high yields with good to excellent enantioselectivity.

Tridentate Sulfoxide-N-olefin Hybrid Ligands in Rhodium-Catalyzed Asymmetric Allylic Substitution.

A well-defined tridentate chiral sulfoxide-N-olefin ligand has been designed and applied in rhodium-catalyzed asymmetric allylic substitutions of racemic allylic carbonates, providing the branched allylic products in good yields with good to high enantioselectivities and excellent regioselectivities. This reaction mechanism, which involves the possible hemilability of olefin coordination on sulfoxide-N-olefin hybrid ligands with rhodium, is elaborated as well.

Hepatocyte growth factor combined with adenosine deaminase as biomarker for diagnosis of tuberculous pleural effusion.

Background: The simple, rapid, and accurate diagnosis of tuberculous pleural effusion (TPE) remains difficult. This study aimed to determine the accuracy of hepatocyte growth factor (HGF) in the diagnosis of TPE. Methods: We quantified the expression of HGF, adenosine deaminase (ADA), and interferon gamma (IFN-γ) in pleural effusion (PE) in 97 TPE subjects and 116 non-TPE subjects using an enzyme-linked immunosorbent assay (ELISA) or a fully automatic biochemical analyzer. The diagnostic performance of these three biomarkers was evaluated using a receiver operating characteristic (ROC) curve of subjects by age and gender. Results: We discovered that the TPE group had much higher levels of HGF than the non-TPE group, regardless of age or gender, and that there was no statistically significant difference between the two groups' levels of HGF expression in peripheral plasma. In female TPE patients aged ≤65 years, the AUCs of TPE and non-TPE diagnosed by HGF, ADA or IFN-γ were 0.988, 0.964, and 0.827, respectively. HGF plus ADA had the highest diagnostic efficacy in female TPE patients aged ≤65 years. With HGF plus ADA having a cut-off value of 0.219 for distinguishing TPE from non-TPE, the area under the curve (AUC), sensitivity (SEN), specificity (SPE), positive predictive value (PPV), and negative predictive value (NPV) were, respectively, 0.998 (95% confidence interval [CI], 0.993-1.000), 100 (95% CI, 89.997-100.000), 96.667 (95% CI, 82.783-99.916), 97.222 (95% CI, 83.594-99.586), and 100. Conclusion: This study confirmed that HGF plus ADA has high diagnostic efficacy in younger female TPE patients and has the potential to be an excellent biomarker.

Characterization of the alternative splicing landscape in lung adenocarcinoma reveals novel prognosis signature associated with B cells.

BACKGROUND: Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death. Malignant pleural effusion (MPE) is a special microenvironment for lung cancer metastasis. Alternative splicing, which is regulated by splicing factors, affects the expression of most genes and influences carcinogenesis and metastasis. METHODS: mRNA-seq data and alternative splicing events in lung adenocarcinoma (LUAD) were obtained from The Cancer Genome Atlas (TCGA). A risk model was generated by Cox regression analyses and LASSO regression. Cell isolation and flow cytometry were used to identify B cells. RESULTS: We systematically analyzed the splicing factors, alternative splicing events, clinical characteristics, and immunologic features of LUAD in the TCGA cohort. A risk signature based on 23 alternative splicing events was established and identified as an independent prognosis factor in LUAD. Among all patients, the risk signature showed a better prognostic value in metastatic patients. By single-sample gene set enrichment analysis, we found that among tumor-infiltrating lymphocytes, B cells were most significantly correlated to the risk score. Furthermore, we investigated the classification and function of B cells in MPE, a metastatic microenvironment of LUAD, and found that regulatory B cells might participate in the regulation of the immune microenvironment of MPE through antigen presentation and promotion of regulatory T cell differentiation. CONCLUSIONS: We evaluated the prognostic value of alternative splicing events in LUAD and metastatic LUAD. We found that regulatory B cells had the function of antigen presentation, inhibited naïve T cells from differentiating into Th1 cells, and promoted Treg differentiation in LUAD patients with MPE.

Ir-Catalyzed Chemo-, Regio-, and Enantioselective Allylic Enolization of 6,6-Dimethyl-3-((trimethylsilyl)oxy)cyclohex-2-en-1-one Involving Keto-Enol Isomerization.

The utilization of 6,6-dimethyl-3-((trimethylsilyl)oxy)cyclohex-2-en-1-one made from an unsymmetrical 4,4-dimethylcyclohexane-1,3-dione in iridium-catalyzed allylic enolization involving keto-enol isomerization is accomplished under mild conditions. The chemoselectivity, regioselectivity, and enantioselectivity are facilitated by the quaternary carbon and adjusting the reaction conditions. This method provides the substituted 2-(but-3-en-2-yl)-3-hydroxy-6,6-dimethylcyclohex-2-en-1-ones in good to high yields with high level of chemo-, regio-, and enantioselectivities. The chiral carbon-fluorine bond formation is induced by an adjacent chiral carbon center of the allylated 3-hydroxy-6,6-dimethylcyclohex-2-en-1-one, as well.

Catalytic Kinetic Resolution by Enantioselective Aromatization: Conversion of Racemic Intermediates of the Barton-Zard Reaction into Enantioenriched 3-Arylpyrroles.

Racemic 3,4-dihydro-2H-pyrroles, hypothetical intermediates of the Barton-Zard reaction, were synthesized in a highly diastereoselective manner and fully characterized for the first time. Kinetic resolution of the dihydropyrroles with a quinine-derived thiourea afforded the (+)-3-arylpyrrole products and recovered (+)-3,4-dihydro-2H-pyrroles with high efficiency (s-factor up to 153). The resolved (+)-3,4-dihydro-2H-pyrroles underwent subsequent aromatization with a quinidine-derived thiourea catalyst to afford (-)-3-arylpyrroles with excellent central-to-axial chirality transfer. In contrast to the well-accepted Barton-Zard mechanism, the aromatization of the 3,4-dihydro-2H-pyrroles in the presence of a bifunctional catalyst is believed to proceed by an unprecedented sequence involving syn elimination of HNO2 and aromatization.

Catalytic Atropenantioselective Heteroannulation between Isocyanoacetates and Alkynyl Ketones: Synthesis of Enantioenriched Axially Chiral 3-Arylpyrroles.

We report herein the first examples of catalytic enantioselective synthesis of axially chiral 3-arylpyrroles. Reaction of α-isocyanoacetates with ß-aryl-α,ß-alkynic ketones in the presence of silver oxide and a phosphine ligand derived from Cinchona alkaloid occurred chemoselectively to afford enantioenriched 3-arylpyrroles in high yields with excellent enantiomeric excesses. The pyrrole ring was constructed de novo in this process.

Erratum: Organocatalytic atroposelective synthesis of axially chiral styrenes.

This corrects the article DOI: 10.1038/ncomms15238.

Organocatalytic atroposelective synthesis of axially chiral styrenes.

Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

Brønsted acid-catalysed enantioselective construction of axially chiral arylquinazolinones.

The axially chiral arylquinazolinone acts as a privileged structural scaffold, which is present in a large number of natural products and biologically active compounds as well as in chiral ligands. However, a direct catalytic enantioselective approach to access optically pure arylquinazolinones has been underexplored. Here we show a general and efficient approach to access enantiomerically pure arylquinazolinones in one-pot fashion catalysed by chiral phosphoric acids. A variety of axially chiral arylquinazolinones were obtained in high yields with good to excellent enantioselectivities under mild condition. Furthermore, we disclosed a method for atroposelective synthesis of alkyl-substituted arylquinazolinones involving Brønsted acid-catalysed carbon-carbon bond cleavage strategy. Finally, the asymmetric total synthesis of eupolyphagin bearing a cyclic arylquinazolinone skeleton was accomplished with an overall yield of 32% in six steps by utilizing the aforementioned methodology.

Construction of Tropane Derivatives by the Organocatalytic Asymmetric Dearomatization of Isoquinolines.

A chiral-NHC-catalyzed highly diastereo- and enantioselective dearomatizing double Mannich reaction of isoquinolines was developed that provides a powerful and straightforward synthetic route toward substituted tropane derivatives with four contiguous stereocenters. A unique feature of this strategy is the use of readily available isoquinolines to provide two reactive sites for dearomatization, thus opening up an unprecedented approach to tropane derivatives with excellent stereoselectivity. The four-component reactions proceeded smoothly with good results. Thus, the present method is suitable for the diversity-oriented synthesis of useful tropane derivatives with high efficiency.

Asymmetric Synthesis of Axially Chiral Isoquinolones: Nickel-Catalyzed Denitrogenative Transannulation.

The first Ni(0)/bis(oxazoline)-catalyzed asymmetric denitrogenative transannulation of 1,2,3-benzotriazin-4(3H)-ones with bulky internal alkynes to form novel axially chiral isoquinolones in an atroposelective manner has been developed. This method provides direct asymmetric access to axially chiral isoquinolones with excellent functional-group tolerance in excellent yields and stereoselectivities from readily available starting materials under mild reaction conditions. These axially chiral isoquinolones exhibit high cytotoxicity against a number of human cancer cell lines. DFT calculations reveal the nature of the transition state in the key annulation step.

Metal-free direct 1,6- and 1,2-difunctionalization triggered by radical trifluoromethylation of alkenes.

A metal-free direct remote C-H functionalization triggered by radical trifluoromethylation of alkenes was explored, realizing highly selective 1,6-difunctionalization of alkenes toward valuable trifluoromethyl α-hydroxycarbonyl compounds. Furthermore, a metal-free direct intermolecular regioselective 1,2-oxytrifluoromethylation of alkenes is also disclosed. With Togni's reagent as both the CF3 source and oxidant, the reaction exhibits a broad substrate scope with excellent functionality tolerance under mild metal-free conditions, thus showing great potential for synthetic utility.

Trifluoromethylation-initiated remote cross-coupling of carbonyl compounds to form carbon-heteroatom/carbon bonds.

By involving the reversal of conventional reactivity expectations without external oxidants, we describe a novel and convenient protocol of remote cross-coupling of carbonyl compounds with a series of common and simple nucleophiles. This cross-coupling is triggered by radical trifluoromethylation of alkenes, thereby achieving highly selective remote difunctionalization of alkenes and α-position of the carbonyl group for facile access to trifluoromethyl α-halo- and α-cyanocarbonyl compounds. The reaction exhibits a broad substrate scope with excellent functionality tolerance and many different types of nucleophiles; further synthetic applicability of the obtained compounds proved to be suitable, thus showing great potential for synthetic utility.

Phosphine-catalyzed remote ß-C-H functionalization of amines triggered by trifluoromethylation of alkenes: one-pot synthesis of bistrifluoromethylated enamides and oxazoles.

An unprecedented phosphine-catalyzed remote ß-CH functionalization of amine derivatives triggered by trifluoromethylation of an alkene with Togni's reagent was disclosed. This reaction proceeded through the highly selective and concomitant activation of an unactivated alkene and the ß-C sp 3H bond of an amine derivative, providing bistrifluoromethylated enamides in excellent yields with good regio-, chemo-, and stereoselectivity. Furthermore, the newly developed one-pot protocol provides a facile and step-economical access to valuable trisubstituted 5-(trifluoromethyl)oxazoles. Mechanistic studies showed that this reaction may initiate with a novel phosphine-catalyzed radical trifluoromethylation of unactivated alkene via a phosphorus radical cation.

Enantioselective C-H bond functionalization triggered by radical trifluoromethylation of unactivated alkene.

An asymmetric unactivated alkene/C-H bond difunctionalization reaction for the concomitant construction of C-CF3 and C-O bonds was realized by using a Cu/Brønsted acid cooperative catalytic system, thus providing facile access to valuable chiral CF3-containing N,O-aminals with excellent regio-, chemo-, and enantioselectivity. Mechanistic studies revealed that this reaction may proceed by an unprecedented 1,5-hydride shift involving activation of unactivated alkenes and a radical trifluoromethylation to initiate subsequent enantioselective functionalization of C-H bonds. Control experiments also suggested that chiral Brønsted acid plays multiple roles and not only controls the stereoselectivity but also increases the reaction rate through activation of Togni's reagent.

Enantioselective transformation of allyl carbonates into branched allyl carbamates by using amines and recycling CO2 under iridium catalysis.

Enantioselective transformation of allyl carbonates into branched allyl carbamates by using amines and recycling CO2 in the presence of an Ir complex and K3PO4 was accomplished. This provided branched allyl carbamates in fair to excellent yields with up to 98:2 regioselectivity and 93 % ee. The role of CO2 in this transformation is discussed as well.

Highly enantioselective kinetic resolution of axially chiral BINAM derivatives catalyzed by a Brønsted acid.

A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid-catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities.

Metal-free direct intramolecular carbotrifluoromethylation of alkenes to functionalized trifluoromethyl azaheterocycles.

The first example of a metal-free direct carbotrifluoromethylation of alkenes using inexpensive TMSCF3 as the CF3 source is described. The methodology not only exhibits high chemoselectivity for this transformation but also expands the substrate scope that is difficult to access by known transition-metal-catalyzed methods.