Intensified electrochemiluminescence and photoluminescence via supramolecular anion recognition interactions.

Herein, intensified electrochemiluminescence (ECL) and photoluminescence (PL) via supramolecular anion recognition interactions are demonstrated. A bisindolylpyrrole derivative with a structure containing two indole groups and 2-hexyl-pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione, BIPPD, was designed and synthesized de novo to induce the enhanced ECL and PL emission based on hydrogen bonding interactions with the dihydrogen phosphate anion. Remarkably, the ECL quantum efficiency and PL quantum yield were discovered to increase up to 5.5-fold and 1.5-fold, respectively, via this anion coordination. Dopant PF6 - was found not to form hydrogen bonds, while HSO4 - doping does slightly with the receptor molecule. There was no enhancement in either ECL or PL in both scenarios, revealing great recognition selectivity of the synthesized BIPPD. Mechanistic studies via 1H NMR, ECL, and PL spectra illustrated that the ECL processes varied in the presence and absence of H2PO4 - doping, thus leading to the understanding of enhanced efficiency. The bisindolylpyrrole derivative will find applications in supramolecular and analytical chemistry via controlled hydrogen bonding interactions.

Sustained remission of Cronkhite-Canada syndrome after corticosteroid and mesalazine treatment: A case report.

BACKGROUND: Cronkhite-Canada syndrome (CCS) is a rare disease of unknown etiology. The optimal treatment for CCS remains unknown. Treatment with corticosteroids is considered the mainstay treatment because of its high efficacy, but the therapeutic strategy for steroid-resistant CCS is not yet established. CASE SUMMARY: This is the case of an 81-year-old woman who was diagnosed with CCS. Given her severe diarrhea, nausea, vomiting, and hypoproteinemia, hormone therapy (40 mg/d) was administered, and the symptoms improved within 1 wk. After 3 mo, the patient had no obvious symptoms. The polyps were significantly reduced on review gastroscopy and colonoscopy, thus hormone reduction gradually began. The hormone level was maintained at 10 mg/d after 6 mo. Despite the age of the patient and the side effects of hormones, the patient had no obvious discomfort. However, hormone drugs were discontinued, and mesalazine was administered orally at 3 g/d. The patient's symptoms continued to improve after a follow-up of 5 years. CONCLUSION: Corticosteroids and mesalazine are potential treatment options for CCS.

Immune modulatory roles of radioimmunotherapy: biological principles and clinical prospects.

Radiation therapy (RT) not only can directly kill tumor cells by causing DNA double-strand break, but also exerts anti-tumor effects through modulating local and systemic immune responses. The immunomodulatory effects of RT are generally considered as a double-edged sword. On the one hand, RT effectively enhances the immunogenicity of tumor cells, triggers type I interferon response, induces immunogenic cell death to activate immune cell function, increases the release of proinflammatory factors, and reshapes the tumor immune microenvironment, thereby positively promoting anti-tumor immune responses. On the other hand, RT stimulates tumor cells to express immunosuppressive cytokines, upregulates the function of inhibitory immune cells, leads to lymphocytopenia and depletion of immune effector cells, and thus negatively suppresses immune responses. Nonetheless, it is notable that RT has promising abscopal effects and may achieve potent synergistic effects, especially when combined with immunotherapy in the daily clinical practice. This systematic review will provide a comprehensive profile of the latest research progress with respect to the immunomodulatory effects of RT, as well as the abscopal effect of radioimmunotherapy combinations, from the perspective of biological basis and clinical practice.

Selective P450BM3 Hydroxylation of Cyclobutylamine and Bicyclo[1.1.1]pentylamine Derivatives: Underpinning Synthetic Chemistry for Drug Discovery.

Achieving single-step syntheses of a set of related compounds divergently and selectively from a common starting material affords substantial efficiency gains when compared with preparing those same compounds by multiple individual syntheses. In order for this approach to be realized, complementary reagent systems must be available; here, a panel of engineered P450BM3 enzymes is shown to fulfill this remit in the selective C-H hydroxylation of cyclobutylamine derivatives at chemically unactivated sites. The oxidations can proceed with high regioselectivity and stereoselectivity, producing valuable bifunctional intermediates for synthesis and applications in fragment-based drug discovery. The process also applies to bicyclo[1.1.1]pentyl (BCP) amine derivatives to achieve the first direct enantioselective functionalization of the bridging methylenes and open a short and efficient route to chiral BCP bioisosteres for medicinal chemistry. The combination of substrate, enzyme, and reaction engineering provides a powerful general platform for small-molecule elaboration and diversification.

The development and application of a novel reagent for fixing red blood cells with glutaraldehyde and paraformaldehyde.

OBJECTIVE: The currently employed red blood cell reagents have a short shelf life. Some hospitals with a small number of specimens will be unable to utilize them within the validity period, resulting in a substantial increase in the purchase price. Therefore, the method of developing long-term red blood cell reagents is a problem worthy of further study. METHODS: In this experiment, the type and concentration of the red blood cell reagent treatment solution were evaluated based on the red blood cell antigen concentration 24 h after treatment. In addition, the qualified glutaraldehyde/paraformaldehyde reagent was stored for six months, and five red blood cell indices were measured every month. At the same time, the detection indices of treated red blood cell reagents and untreated red blood cell reagents were compared. RESULTS: It was discovered that treated red blood cells containing 0.005% GA and 0.05% PFA were more suitable for the preservation of red blood cells than other treated concentrations, and the preservation time could reach six months. The test tube method (n = 24) and microcolumn gel card (n = 35) were used to determine the accuracy of the treated blood cells containing 0.005% glutaraldehyde +0.05% paraformaldehyde, with an accuracy of 100%. CONCLUSION: This experiment resulted in the development of a novel reagent for treating red blood cells with glutaraldehyde/paraformaldehyde fixed solution that can effectively prolong its storage time by two to three times that of red blood cell reagents currently on the market.

Mapping the Porous and Chemical Structure-Function Relationships of Trace CH3I Capture by Metal-Organic Frameworks using Machine Learning.

Large-scale computational screening has become an indispensable tool for functional materials discovery. It, however, remains a challenge to adequately interrogate the large amount of data generated by a screening study. Here, we computationally screened 1087 metal-organic frameworks (MOFs), from the CoRE MOF 2014 database, for capturing trace amounts (300 ppmv) of methyl iodide (CH3I); as a primary representative of organic iodides, CH3129I is one of the most difficult radioactive contaminants to separate. Furthermore, we demonstrate a simple and general approach for mapping and interrogating the high-dimensional structure-function data obtained by high-throughput screening; this involves learning two-dimensional embeddings of the high-dimensional data by applying unsupervised learning to encoded structural and chemical features of MOFs. The resulting various porous and chemical structure-function maps are human-interpretable, revealing not only top-performing MOFs but also complex structure-function correlations that are hidden when inspecting individual MOF features. These maps also alleviate the need of laborious visual inspection of a large number of MOFs by clustering similar MOFs, per the encoding features, into defined regions on the map. We also show that these structure-function maps are amenable to supervised classification of the performances of MOFs for trace CH3I capture. We further show that the machine-learning models trained on the 1087 CoRE MOFs can be used to predict an unseen set of 250 MOFs randomly selected from a different MOF database, achieving high prediction accuracies.

LncRNA-84277 is involved in chronic pain-related depressive behaviors through miR-128-3p/SIRT1 axis in central amygdala.

Long-term chronic pain can lead to depression. However, the mechanism underlying chronic pain-related depression remains unclear. Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase (HDAC). Our previous studies have demonstrated that SIRT1 in the central nucleus of the amygdala (CeA) is involved in the development of chronic pain-related depression. In addition, increasing studies have indicated that long non-coding RNAs (lncRNAs) play a vital role in the pathogenesis of pain or depression. However, whether lncRNAs are involved in SIRT1-mediated chronic pain-related depression remains largely unknown. In this study, we identified that a novel lncRNA-84277 in CeA was the upstream molecule to regulate SIRT1 expression. Functionally, lncRNA-84277 overexpression in CeA significantly alleviated the depression-like behaviors in spared nerve injury (SNI)-induced chronic pain rats, whereas lncRNA-84277 knockdown in CeA induced the depression-like behaviors in naïve rats. Mechanically, lncRNA-84277 acted as a competing endogenous RNA (ceRNA) to upregulate SIRT1 expression by competitively sponging miR-128-3p, and therefore improved chronic pain-related depression-like behaviors. Our findings reveal the critical role of lncRNA-84277 in CeA specifically in guarding against chronic pain-related depression via a ceRNA mechanism and provide a potential therapeutic target for chronic pain-related depression.

In Silico Tuning of the Pore Surface Functionality in Al-MOFs for Trace CH3I Capture.

Aluminum (Al)-based metal-organic frameworks (MOFs) have been shown to have good stability toward γ irradiation, making them promising candidates for durable adsorbents for capturing volatile radioactive nuclides. In this work, we studied a series of existing Al-MOFs to capture trace radioactive organic iodide (ROI) from a gas composition (100 ppm CH3I, 400 ppm CO2, 21% O2, and 78% N2) resembling the off-gas composition from reprocessing the used nuclear fuel using Grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) calculations. Based on the results and understanding established from studying the existing Al-MOFs, we proceed by functionalizing the top-performing CAU-11 with different functional groups to propose better MOFs for ROI capture. Our study suggests that extraordinary ROI adsorption and separation capability could be realized by -SO3H functionalization in CAU-11. It was mainly owing to the joint effect of the enhanced pore surface polarity arising from -SO3H functionalization and the µ-OH group of CAU-11.

Plantaginis Semen polysaccharides ameliorate renal damage through regulating NLRP3 inflammasome in gouty nephropathy rats.

Gouty nephropathy (GN) is considered to be a prevalent renal disease and is an inflammatory event mainly induced by MSU crystals. Plantaginis Semen is a traditional Chinese herb that has been used in the treatment of gout, gouty arthritis and GN, but the mechanism and ingredients have been unclear. In this study, we explored and evaluated the preliminary structural characterizations of Plantaginis Semen polysaccharides (PSPs) and the activity of protecting against renal damage in GN rats. Three polysaccharide fractions, PSP-D, PSP-H and PSP-S, were sequentially extracted by different processes from the seed of Plantago asiatica L. The Fourier transform infrared spectral (FTIR) results showed that there were significant differences between PSP-S and the other two polysaccharides (PSP-D and PSP-H). PSP-D and PSP-H have pyrene monomers and linkages of ß-glycosides in their structures, and PSP-S has furanoside in the molecular structure. The scanning electron microscope (SEM) images of three polysaccharides showed that PSP-D has a smooth surface and a small curve, PSP-H is block-like and uneven in magnitude, whereas PSP-S is sea-tent-like and its surface is very distinct from the others. Main components and molar ratios are also different. Rats were randomly divided into six groups (n1/6 8 per group): the control group, model group, positive group, and three treatment groups (PSP-D, PSP-H and PSP-S). For all groups except the control group, rats were intragastrically administered the adenine suspension (50 mg kg-1 d-1) and fed with a high-yeast diet (15 g kg-1 d-1) for 28 days. On the 9th day, the control group and the model group were administered normal saline at the same time. Treatment groups were individually given corresponding drugs for 20 days. We found that PSPs could prevent renal damage, including decreasing the inflammatory response and regulating the (NOD)-like receptor protein 3 (NLRP3) protein in renal tissue. The underlying mechanism was related to NLRP3 inflammasome signal pathways, and it could take effect through the down-regulation of the protein expression levels of NLRP3, ASC and caspase-1 and inhibit the release of downstream inflammatory factors. PSPs are promising polysaccharides that could protect against renal injury through ameliorating renal inflammation in GN rats. Plantaginis Semen polysaccharides are potential functional food ingredients or pharmacological agents for treating GN in clinical practice.

SIRT3 alleviates neuropathic pain by deacetylating FoxO3a in the spinal dorsal horn of diabetic model rats.

BACKGROUND: The underlying mechanisms of neuropathic pain remain unclear. This work aimed to investigate the role of Sirtuin3 (SIRT3), an nicotinamide adenosine dinucleotide+-dependent histone deacetylase, in the development of neuropathic pain induced by type 2 diabetes mellitus (T2DM) and to explore the associated mechanisms. METHODS: Diabetic neuropathic pain (DNP) in rats was induced by high-fat diet/low-dose streptozotocin. The pain behaviors were examined using the von Frey and Hargreaves tests. The levels of SIRT3, manganese superoxide dismutase (MnSOD) and catalase (CAT) were determined using Western blot and RT-qPCR. The acetylation, phosphorylation and ubiquitination of forkhead box class O3a (FoxO3a) were analyzed by immunoprecipitation and Western blot. RESULTS: SIRT3 expression and activity were significantly reduced in the spinal dorsal horn of DNP model rats. Overexpression of spinal SIRT3 reversed the pain hypersensitivity in the DNP model rats, but knockdown of spinal SIRT3 mimicked the pain effect, eliciting pain hypersensitivity in normal rats. Moreover, overexpression of spinal SIRT3 in DNP model rats increased the FoxO3a level and upregulated the antioxidant genes MnSOD and CAT by deacetylating FoxO3a and inhibiting FoxO3a phosphorylation and ubiquitination. Knockdown of spinal SIRT3 in normal rats decreased the FoxO3a level and downregulated MnSOD and CAT by inhibiting the deacetylation of FoxO3a and further increasing FoxO3a phosphorylation and ubiquitination. CONCLUSIONS: These results suggest that, by deacetylating FoxO3a and further reducing its phosphorylation, ubiquitination and degradation in the spinal dorsal horn, SIRT3 stabilizes FoxO3a protein and inhibits oxidative stress, resulting in pain alleviation in T2DM model rats.

Revealing Crystallization-Induced Blue-Shift Emission of a Di-Boron Complex by Enhanced Photoluminescence and Electrochemiluminescence.

Elucidating the effects of crystallization-induced blue-shift emission of a newly synthesized di-boron complex (DBC) by enhanced photoluminescence (PL) and electrochemiluminescence (ECL) in the annihilation pathway was realized for the first time. The 57 nm blue-shift and great enhancement in the crystalline lattice relative to the DBC solution were attributed to the restriction of intramolecular rotation (RIR) and confirmed by PL imaging, X-ray diffraction, as well as DFT calculations. It was discovered that ECL at crystalline film/solution interfaces can be further enhanced by means of both co-reactant route and RIR. The RIR contributions with co-reactant increased ECL up to 5 times more. Very interestingly, the co-reactant system was found to give off a red-shifted light emission. Mechanistic studies reveal that a difference between location of the ECL in the co-reactant route and that in the annihilation pathway leads to an alternative emission wavelength.

Quercetin attenuates diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn of db/db mice.

Numerous studies indicate that the changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons contributes to the development and maintenance of neuropathic pain. Quercetin, a bioflavonoid compound, has been shown to have analgesic effect in several pain models. However, the underlying mechanism for quercetin to allieviate pain is unclear. Therefore, in this study, we observed the effect of quercetin on diabetic neuropathic pain in db/db mice and explored the underlying mechanisms. Our results showed that chronic quercetin treatment alleviated thermal hyperalgesia in db/db mice. Moreover, quercetin administration significantly reduced the total dendritic length, the number of dendritic branches, and the dendritic spine density in the spinal dorsal horn neurons of db/db mice. Meanwhile, the up-regulated expressions of synaptic plasticity-associated proteins postsynaptic density protein 95 (PSD-95) and synaptophysin in spinal dorsal horn of db/db mice were decreased by quercetin treatment. In addition, quercetin treatment reduced the phosphorylated levels of mammalian target of rapamycin (mTOR) and p70 ribosomal S6 kinase (p70S6K) in spinal dorsal horn of db/db mice. These results demonstrate that quercetin may alleviate diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons of db/db mice. These findings suggest that quercetin may be a promising therapeutic drug in neuropathic pain.

Unconventional Pyridyl Ligand Inclusion within a Flexible Metal-Organic Framework Bearing an N,N'-Diethylformamide (DEF)-Solvated Cd5 Cluster Secondary Building Unit.

A cationic three-dimensional (3D) metal-organic framework (MOF) sustained by an N,N'-diethylformamide (DEF)-solvated zigzag-shaped Cd5 cluster secondary building unit (SBU), [Et2 NH2 ]2 [Cd5 (BTB)4 (DEF)2 ] ⋅ 4.75DEF (1 a, H3 BTB=benzene-1,3,5-tribenzoic acid) shows flexible framework behavior and undergoes solvate exchange with CHCl3 to yield [Et2 NH2 ]2 [Cd5 (BTB)4 (DEF)2 ] ⋅ xCHCl3 (1 b) accompanied by changes to pore sizes and shapes. Unexpectedly, the DEF solvates coordinated to the central Cd2+ could not be replaced by strongly donor pyridyl and dipyridyl ligands. Additionally, more electron-deficient pyridyls preferentially coordinated to the flanking Cd2+ of the Cd5 SBU, as exemplified by [Et2 NH2 ]2 [Cd5 (BTB)4 (DEF)2 (PyCHO)2 ] ⋅ xSol (2 a, PyCHO=4-pyridinealdehyde) and [Et2 NH2 ]2 [Cd5 (BTB)4 (DEF)2 (PyAc)2 ] ⋅ xSol (2 b, PyAc=4-acetylpyridine). Density functional theory (DFT) calculations were used to understand these counterintuitive observations.

Berberine mitigates high glucose-induced podocyte apoptosis by modulating autophagy via the mTOR/P70S6K/4EBP1 pathway.

AIMS: This study aimed to investigate the characteristics and mechanism of autophagy on podocyte apoptosis under high glucose (HG) conditions and further explore the effect of berberine on podocyte autophagy, apoptosis and the potential mechanism. MATERIALS AND METHODS: The levels of LC3II/I in podocytes stimulated with HG were detected at 0, 2, 4, 8, 12, 24, 36 and 48 h by western blotting. CCK-8 was used to detect the viability of podocytes. The level of autophagy was detected by western blotting, transmission electron microscopy and immunofluorescence. Podocyte apoptosis was analysed by using Hoechst staining, western blotting, annexin V/propidium iodide dual staining, and confocal microscopy. Then, podocytes were transfected with siRNA to silence mTOR, and the expression levels of proteins and mRNA involved in the mTOR/P70S6K/4EBP1 pathway were further investigated by western blotting and qRT-PCR. KEY FINDINGS: In this study, we found significantly reduced LC3II/LC3I and increased p62 in podocytes stimulated with HG for 24 h, and the level of autophagy reached a minimum at 24 h. Berberine restored podocyte viability and significantly attenuated HG-mediated inhibition of autophagy, as evidenced by the increased expression of LC3II/LC3I, the number of autophagosomes and the inhibition of p62. Moreover, berberine counteracted HG-induced podocyte apoptosis and injury, which was negatively correlated with the autophagy effect. Notably, silencing mTOR with siRNA augmented the inhibition of P70S6k and 4EBP1 phosphorylation, which was similar to the effect of berberine. SIGNIFICANCE: Berberine activates podocyte autophagy by inhibiting the mTOR/P70S6K/4EBP1 signaling pathway, thereby alleviating podocyte apoptosis.

Facile synthesis and efficient electrochemiluminescence of a readily accessible pyridopyrimidine.

Through a facile one-pot three-component reaction and a subsequent acetylation strategy, a novel greenish-blue fluorescent 4-imino-4H-pyrido[1,2-a]pyrimidine-3-carbonitrile (IPPC) was synthesized. Electrochemiluminescence (ECL) of IPPC was firstly found to produce efficient emission at 500 nm with reducing coreactants. Its very similar ECL and PL spectra suggest that ECL production is mainly from the monomeric excited states.

[Construction of Fat-1 eukaryotic expression vector of excision markers and the establishment of transgenic sheep cell lines].

In order to establish marker-free transgenic cell lines, we cloned Fat-1 gene, attB and Loxp sequences by PCR. Then we inserted these sequences to pN1-EGFP vector and got pEGFP-N1-Fat-1 expression vector. PhiC31 integrase mRNA which was generated by in vitro transcription and a pEGFP-N1-Fat-1 expression vector co-electroporated into sheep fetal fibroblasts, and then we got transgenic cell lines expressing green fluorescence. Prokaryotic expression and purification of Cre recombinant protein was performed. Cre recombinant protein was transducted into stably-transfected cell colonies. We identified cell colonies by sequencing and established marker-free transgenic cell lines and eventually- established marker-free transgenic cell lines which were building more safely basic for producing Fat-1 transgenic animals.

Four supramolecular isomers of dichloridobis(1,10-phenanthroline)cobalt(II): synthesis, structure characterization and isomerization.

Crystal engineering can be described as the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding to design new solids with desired physical and chemical properties. Free-energy differences between supramolecular isomers are generally small and minor changes in the crystallization conditions may result in the occurrence of new isomers. The study of supramolecular isomerism will help us to understand the mechanism of crystallization, a very central concept of crystal engineering. Two supramolecular isomers of dichloridobis(1,10-phenanthroline-κ(2)N,N')cobalt(II), [CoCl2(C12H8N2)2], i.e. (IA) (orthorhombic) and (IB) (monoclinic), and two supramolecular isomers of dichloridobis(1,10-phenanthroline-κ(2)N,N')cobalt(II) N,N-dimethylformamide monosolvate, [CoCl2(C12H8N2)2]·C3H7NO, i.e. (IIA) (orthorhombic) and (IIB) (monoclinic), were synthesized in dimethylformamide (DMF) and structurally characterized. Of these, (IA) and (IIA) have been prepared and structurally characterized previously [Li et al. (2007). Acta Cryst. E63, m1880-m1880; Cai et al. (2008). Acta Cryst. E64, m1328-m1329]. We found that the heating rate is a key factor for the crystallization of (IA) or (IB), while the temperature difference is responsible for the crystallization of (IIA) or (IIB). Based on the crystallization conditions, isomerization behaviour, the KPI (Kitajgorodskij packing index) values and the density data, (IB) and (IIA) are assigned as the thermodynamic and stable kinetic isomers, respectively, while (IA) and (IIB) are assigned as the metastable kinetic products. The 1,10-phenanthroline (phen) ligands interact with each other through offset face-to-face (OFF) π-π stacking in (IB) and (IIB), but by edge-to-face (EF) C-H...π interactions in (IA) and (IIA). Meanwhile, the DMF molecules in (IIB) connect to neighbouring [CoCl2(phen)2] units through two C-H...Cl hydrogen bonds, whereas there are no obvious interactions between DMF molecules and [CoCl2(phen)2] units in (IIA). Since OFF π-π stacking is generally stronger than EF C-H...π interactions for transition-metal complexes with nitrogen-containing aromatic ligands, (IIA) is among the uncommon examples that are stable and densely packed but that do not following Etter's intermolecular interaction hierarchy.

4,4'-Bipyridine-1,1'-diium acetylenedicarboxylate: a new member of the (H2bipy)[Cu(ox)2] (bipy is 4,4'-bipyridine and ox is oxalate) family.

4,4'-Bipyridine-1,1'-diium (H2bipy) acetylenedicarboxylate, C10H12N2(2+)·C4O4(2-), (1), is a new member of a family of related structures with similar unit-cell parameters. The structures in this family reported previously [Chen et al. (2012). CrystEngComm, 14, 6400-6403] are (H2bipy)[Cu(ox)2] (ox is oxalate), (2), (H2bipy)[NaH(ox)2], (3), and (H2bipy)[H2(ox)2], (4). Compound (1) has a one-dimensional structure, in which H2bipy(2+) cations and acetylenedicarboxylate (ADC(2-)) anions are linked through a typical supramolecular synthon, i.e. R2(2)(7), and form linear `-cation-anion-' ribbons. Through an array of nonclassical C-H...O hydrogen bonds, adjacent ribbons interact to give two-dimensional sheets. These sheets stack to form a layered structure via π-π interactions between the H2bipy(2+) cations of neighbouring layers. The supramolecular isostructurality of compounds (1)-(4) is ascribed to the synergistic effect of multiple interactions in these structures. The balanced strong and weak intermolecular interactions stabilizing this structure type include strong charge-assisted N-H...O hydrogen bonds, C-H...O contacts and π-π interactions.

Highly enantioselective (-)-sparteine-mediated lateral metalation-functionalization of remote silyl protected ortho-ethyl N,N-dialkyl aryl O-carbamates.

We report the enantioselective, lateral deprotonation of ortho-protected or functionalized tertiary N,N-dialkyl aryl O-carbamates 5-7 (Scheme 2 ) and meta-protected carbamates 14, 15, and 20 (Schemes 5 and 7 ) by s-BuLi/(-)-sparteine and subsequent quench with a variety of electrophiles to give products 11-13 and 16, 17, and 21 in yields up to 96% and enantiomeric ratios up to 99:1. The influence of organolithium reagents, ratio of organolithium/(-)-sparteine pair versus N,N-dialkyl aryl O-carbamate starting materials, temperature, solvents, electrophiles, substituents located ortho or meta to the O-carbamate moiety, and O-carbamate N-substituents was investigated. The identical absolute configuration of the stereogenic center of the major enantiomers of the products, as established by single-crystal X-ray analysis for substrates (S)-11c, (S)-19, and (S)-21a, provides evidence for a consistent stereochemical course in the enantioselective deprotonation. Mechanistic investigations, including an estimate of the configurational stability of the benzyllithium species 9 (starting from 12e; Scheme 8 ) and 23 (starting from 17e; Scheme 9 ), both derived by tin-lithium exchange, and 24 (starting from 20; Scheme 9 ) are reported. The experimental results, together with semiempirical molecular orbital calculations (PM3/SMD), are consistent with a process in which enantioinduction occurs in the deprotonation step (Scheme 11 ).

Crystal structure of tetra-kis-(µ-n-butyrato-κ(2) O:O')bis-[chlorido-rhenium(III)](Re-Re).

With an inversion center at the mid-point of the two Re(III) atoms, the title compound, [Re2Cl2{O2C(CH2)2CH3}4], exhibits a paddle-wheel or lantern-type structure with four n-butyrate groups bridging two Re(III) atoms in a syn-syn fashion. The axial chloride ligands together with the Re-Re quadruple bond [2.2330 (3) Å] complete an essentially octa-hedral geometry around each Re(III) atom. There is little distortion, with an Re-Re-Cl bond angle of 176.18 (3)° and typical cis-O-Re-O bond angles ranging from 89.39 (11) to 90.68 (11)°. There are two mol-ecules in the unit cell, and no significant inter-molecular inter-actions were noticed between mol-ecules in the crystal.