Formation of Optically Pure Cyclic Amines by Intramolecular Conjugate Displacement

Intramolecular conjugate displacement (ICD) has been applied to the Morita–Baylis–Hillman adducts formed from (5<i>S</i>)-5-(<i>l</i>-menthyloxy)-2­(5<i>H</i>)-furanone and aldehydes that carry a protected β- or γ-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center α to nitrogen

Formation of Optically Pure Cyclic Amines by Intramolecular Conjugate Displacement

Intramolecular conjugate displacement (ICD) has been applied to the Morita–Baylis–Hillman adducts formed from (5<i>S</i>)-5-(<i>l</i>-menthyloxy)-2­(5<i>H</i>)-furanone and aldehydes that carry a protected β- or γ-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center α to nitrogen

Formation of Optically Pure Cyclic Amines by Intramolecular Conjugate Displacement

Intramolecular conjugate displacement (ICD) has been applied to the Morita–Baylis–Hillman adducts formed from (5<i>S</i>)-5-(<i>l</i>-menthyloxy)-2­(5<i>H</i>)-furanone and aldehydes that carry a protected β- or γ-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center α to nitrogen

Formation of Optically Pure Cyclic Amines by Intramolecular Conjugate Displacement

Intramolecular conjugate displacement (ICD) has been applied to the Morita–Baylis–Hillman adducts formed from (5<i>S</i>)-5-(<i>l</i>-menthyloxy)-2­(5<i>H</i>)-furanone and aldehydes that carry a protected β- or γ-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center α to nitrogen

A General Route to 1,3′-Bipyrroles

A general method is described for the synthesis of 1,3′-bipyrroles. The route involves constructing a pyrrole ring on the nitrogen of a substituted 1<i>H</i>-pyrrole, so as to generate the 1,3′-bipyrrole. In this approach the nitrogen of the starting pyrrole was alkylated with a special Michael acceptor having an allylic leaving group, and the product was then modified in such a way that the second pyrrole ring could be formed by a Paal–Knorr reaction. Two variants of this sequence were examined, one of which led to formation of a 3-hydroxypyridine instead of the second pyrrole ring; the other variant used phenacyl bromide instead of the special Michael acceptor

A General Route to 1,3′-Bipyrroles

A general method is described for the synthesis of 1,3′-bipyrroles. The route involves constructing a pyrrole ring on the nitrogen of a substituted 1<i>H</i>-pyrrole, so as to generate the 1,3′-bipyrrole. In this approach the nitrogen of the starting pyrrole was alkylated with a special Michael acceptor having an allylic leaving group, and the product was then modified in such a way that the second pyrrole ring could be formed by a Paal–Knorr reaction. Two variants of this sequence were examined, one of which led to formation of a 3-hydroxypyridine instead of the second pyrrole ring; the other variant used phenacyl bromide instead of the special Michael acceptor

Novel and potent Lewis acid catalyst: Br₂-catalyzed Friedel–Crafts reactions of naphthols with aldehydes

<p>A discovery that the inexpensive Br₂ can serve as a potent Lewis acid catalyst for bis(2-hydroxy-1-naphthyl)methanes synthesis is presented. Under the catalysis of Br₂ at room temperature, naphthols reacted smoothly with various aldehydes with high efficiency and broad substrate scope. This reaction used to require highly acidic conditions and/or high temperature and/or pressure, and sometimes featured poor yields. Moreover, theoretical calculations suggested that Br₂ is a potent Lewis acid to activate the carbonyl group, yet it was not the primary cause for the remarkable activity of Br₂ in the current communication.</p

Biomass-Derived Carbon Fiber Aerogel as a Binder-Free Electrode for High-Rate Supercapacitors

A flexible carbon fiber aerogel with a very high surface area for supercapacitor application is reported by carbonization and chemical activation of low-cost natural cotton with KOH. The carbon fibers in the aerogel present as a twisted and tubular structure. Depending on the amount of KOH used in the activation process, the specific surface area of aerogels ranges from 1536 to 2436 m² g^–1, while their electrical conductivity remains ∼860 S m^–1. In spite of pore size in the range of 1.0–4.0 nm and pore volume mainly contributed by micropores, the carbon aerogel exhibits a high specific capacitance of 283 F g^–1 (1 A g^–1) in 6 M KOH aqueous electrolyte and retains a high capacitance retention of 224 F g^–1 at current density up to 100 A g^–1. Importantly, a symmetric capacitor built with the aerogel electrodes exhibits a rather small time constant (0.56 s). The superior capacitive performance of a CF electrode is closely related to its distinct structural advantage. The tubular carbon fibers that are several millimeters in length offer ultralong electronic and ionic pathways, while plenty of nanopores on the fiber walls created by KOH activation enable fast ion transport across the walls. Our results demonstrate that capacitive performance of the traditional microporous carbon, which is characterized by poor ion kinetics, can be significantly enhanced by properly engineering the electrode architecture

Experimental and theoretical study of I₂-catalyzed dialkenyl oxindoles synthesis from isatins and α-cyano ketene ethylene dithioacetal

<p>An I₂-catalyzed synthesis of dialkenyl oxindoles from isatins and α-cyano ketene ethylene dithioacetal is described. Both electron-withdrawing groups (EWGs) and alkylthio groups exert effects on the reactivities of ketene dithioacetals. Density functional theory (DFT) calculations suggested that the highest negative charge density on the α-carbon of α-cyano ketene ethylene dithioacetal and the largest positive charge on C(3) of the related key intermediate are both responsible for the superior activity of α-cyano ketene ethylene dithioacetal. The cationic intermediate derived from 2-(1,3-dithian-2-ylidene)acetonitrile is the most stable but the least positive, thus the corresponding alkenylhydroxyoxindole is the thermally stable and separable product. Other ketene dithioacetals are less nucleophilic, and their corresponding cationic intermediates are probably not positive enough to enable further transformation.</p

LadS was involved in the MiaB-mediated regulation of T3SS gene expression.

(A) Relative fluorescence intensity of the pLadS-gfp transcriptional fusion measured in the wild-type PAO1 strain and the ΔmiaB mutant. (B) Relative fluorescence intensity of the pRetS-gfp transcriptional fusion measured in the wild-type PAO1 strain and the ΔmiaB mutant. (C) Relative expression of the ladS gene in the wild-type PAO1 and ΔmiaB mutant measured by RT-qPCR. (D) Relative fluorescence intensity of the pLadS-gfp transcriptional fusion measured in the wild-type PAO1 strain and the ΔmiaB mutant when cell growth at the OD600 of 0.5, 1.0, 1.5 and 2.0. (E) β-galactosidase activity of the PexsCEBA-lacZ transcriptional fusion in the wide-type PAO1 strain, ΔmiaB, ΔladS and the ΔmiaBΔladS mutants as well as the ΔmiaBΔladS mutant with in trans expression of miaB and ladS. (F) Production of the ExoS protein measured by western blot in the wide-type PAO1 strain, ΔmiaB, ΔladS and the ΔmiaBΔladS mutants as well as the ΔmiaBΔladS mutant with in trans expression of miaB and ladS. ns, not significant; *, P P P t test.</p