Decarboxylative alkenylation.

Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids. The activating principles used in amide-bond synthesis can therefore be used, with nickel- or iron-based catalysis, to extract carbon dioxide from a carboxylic acid and economically replace it with an organozinc-derived olefin on a molar scale. We prepare more than 60 olefins across a range of substrate classes, and the ability to simplify retrosynthetic analysis is exemplified with the preparation of 16 different natural products across 10 different families.

Synthesis of Natural (-)-Antrocin and its Enantiomer via Stereoselective Aldol Reaction.

The total synthesis of (-)-antrocin and its enantiomer are presented. Antrocin (-)-1 is an important natural product which acts as an antiproliferative agent in a metastatic breast cancer cell line (IC50: 0.6 µM). The key features of this synthesis are: (a) selective anti-addition of trimethylsilyl cyanide (TMSCN) to α,ß-unsaturated ketone; (b) resolution of (±)-7 using chiral auxiliary L-dimethyl tartrate through formation of cyclic ketal diastereomers followed by simple column chromatography separation and acid hydrolysis; (c) substrate-controlled stereoselective aldol condensation of (+)-12 with monomeric formaldehyde and pyridinium chlorochromate (PCC) oxidation for synthesis of essential lactone core in (-)-14; and (d) non-basic Lombardo olefination of the carbonyl at the final step to yield (-)-antrocin. In addition, (+)-9 cyclic ketal diastereomer was converted to (+)-antrocin with similar reaction sequences.

Production of tartrates by cyanide-mediated dimerization of glyoxylate: a potential abiotic pathway to the citric acid cycle.

An abiotic formation of meso- and DL-tartrates in 80% yield via the cyanide-catalyzed dimerization of glyoxylate under alkaline conditions is demonstrated. A detailed mechanism for this conversion is proposed, supported by NMR evidence and (13)C-labeled reactions. Simple dehydration of tartrates to oxaloacetate and an ensuing decarboxylation to form pyruvate are known processes that provide a ready feedstock for entry into the citric acid cycle. While glyoxylate and high hydroxide concentration are atypical in the prebiotic literature, there is evidence for natural, abiotic availability of each. It is proposed that this availability, coupled with the remarkable efficiency of tartrate production from glyoxylate, merits consideration of an alternative prebiotic pathway for providing constituents of the citric acid cycle.

Nanoscale amphiphilic macromolecules with variable lipophilicity and stereochemistry modulate inhibition of oxidized low-density lipoprotein uptake.

Amphiphilic macromolecules (AMs) based on carbohydrate domains functionalized with poly(ethylene glycol) can inhibit the uptake of oxidized low density lipoprotein (oxLDL) and counteract foam cell formation, a key characteristic of early atherogenesis. To investigate the influence of lipophilicity and stereochemistry on the AMs' physicochemical and biological properties, mucic acid-based AMs bearing four aliphatic chains (2a) and tartaric acid-based AMs bearing two (2b and 2l) and four aliphatic chains (2g and 2k) were synthesized and evaluated. Solution aggregation studies suggested that both the number of hydrophobic arms and the length of the hydrophobic domain impact AM micelle sizes, whereas stereochemistry impacts micelle stability. 2l, the meso analogue of 2b, elicited the highest reported oxLDL uptake inhibition values (89%), highlighting the crucial effect of stereochemistry on biological properties. This study suggests that stereochemistry plays a critical role in modulating oxLDL uptake and must be considered when designing biomaterials for potential cardiovascular therapies.

Synthesis of tartaric acid analogues of FR258900 and their evaluation as glycogen phosphorylase inhibitors.

Di-O-cinnamoylated, -p-coumaroylated, and -feruloylated d-, l- and meso-tartaric acids were synthesized as analogues of the natural product FR258900, a glycogen phosphorylase (GP) inhibitor with in vivo antihyperglycaemic activity. The new compounds inhibited rabbit muscle GP in the low micromolar range, and bound to the allosteric site of the enzyme. The best inhibitor was 2,3-di-O-feruloyl meso-tartaric acid and had Ki values of 2.0µM against AMP (competitive) and 3.36µM against glucose-1-phosphate (non-competitive).

Design, synthesis, and application of tartaric acid derived N-spiro quaternary ammonium salts as chiral phase-transfer catalysts.

A novel class of tartaric acid-derived N-spiro quaternary ammonium salts was synthesised starting from known TADDOLs. These compounds were found to catalyse the asymmetric α-alkylation of glycine Schiff bases with high enantioselectivities and in good yields.

ESI-MS investigation of solvent effects on the chiral recognition capacity of tartar emetic towards neutral side-chain amino acids.

The effect of solvent systems on previously-reported ESI-MS based proton-assisted enantioselective molecular recognition phenomena of tartar emetic, L-antimony(III)-tartrate, was evaluated. This was achieved by carrying out a series of competitive binding experiments using chiral selectors, bis(sodium) D- and -L-antimony(III)-tartrates with chiral selectands, neutral side-chain amino acid enantiomeric isotopomers of alanine (Ala), valine (Val), leucine (Leu) and phenylalanine (Phe), in three different solvent systems, ACN/H(2)O (75/25 v/v), H(2)O (100%) and H(2)O/MeOH (25/75 v/v). Observations from these experiments suggest that the effect of solvent systems on previously reported proton-assisted chiral recognition capacity of D,L-antimony(III)-tartrates is small, but not negligible. It was observed that an ACN/H(2)O (75/25 v/v) solvent system facilitates and enhances the chiral discrimination capacity of protonated {[D,L-Sb(2)-tar(2)][H]}(-) ionic species. Further, amino acid enantiomers showed a general trend of increasing selectivity order, Val ≤ Ala < Leu ≈ Phe towards the protonated {[D,L-Sb(2)-tar(2)][H]}(-) ionic species which was independent of the solvent system employed. The lack of enantioselective binding for {[D,L-Sb(2)-tar(2)]}(2-) ionic species was consistently recorded in respective mass spectra from all performed experiments, which suggests that ESI-friendly solvent systems have no effect and do not influence this phenomenon.

Design, Synthesis, and Activity Evaluation of Stereoconfigured Tartarate Derivatives as Potential Anti-inflammatory Agents In Vitro and In Vivo.

Preclinical and clinical data reveal that inflammation is strongly correlated with the pathogenesis of a number of diseases including those of cancer, Alzheimer, and diabetes. The inflammatory cascade involves a multitude of cytokines ending ultimately with the activation of COX-2/LOX for the production of prostaglandins and leukotrienes. While the available inhibitors for these enzymes suffer from nonoptimal selectivity, in particular for COX-2, we present here the results of purposely designed tartarate derivatives that exhibit favorable selectivity and significant effectiveness against COX-2 and LOX. Integrated approaches of molecular simulation, organic synthesis, and biochemical/physical experiments identified 15 inhibiting COX-2 and LOX with respective IC50 4 and 7 nM. At a dose of 5 mg kg-1 to Swiss albino mice, 15 reversed algesia by 65% and inflammation by 33% in 2-3 h. We find good agreement between experiments and simulations and use the simulations to rationalize our observations.

Total regioselective control of tartaric acid.

An efficient strategy to synthesize tartaric acid building blocks for totally regioselective transformations or derivatizations was disclosed. Starting from l-tartaric acid or l-dimethyl tartrate, respectively, we obtained type I and II building blocks with orthogonal sets of protecing groups (4-8 steps, 38-56% overall yield).

Structure and activity relationships of tartrate-based TACE inhibitors.

The syntheses and structure-activity relationships of the tartrate-based TACE inhibitors are discussed. The optimization of both the prime and non-prime sites led to compounds with picomolar activity. Several analogs demonstrated good rat pharmacokinetics.

Diastereoselective hydrophosphonylation of imines using (R,R)-TADDOL phosphite. Asymmetric synthesis of alpha-aminophosphonic acid derivatives.

Efficient synthesis of alpha-aminophosphonic acid derivatives is achieved, the key step being a diastereoselective hydrophosphonylation of N-diphenylphosphinyl imines using a readily available chiral cyclic (R,R)-TADDOL-phosphite derived from inexpensive natural tartaric acid.

Synthesis and characterization of long-chain tartaric acid diamides as novel ceramide-like compounds.

Ceramides play a crucial role in the barrier function of the skin as well as in transmembrane signaling. In this study long aliphatic chain tartaric acid diamides able to replace ceramides in an in vitro model of the stratum corneum lipid matrix due to their similar physico-chemical properties were synthesized from diacetoxysuccinic anhydride in four steps. Their pro-apoptotic effect on fibroblast cells was also investigated.

Synthesis of acetal protected building blocks using flow chemistry with flow I.R. analysis: preparation of butane-2,3-diacetal tartrates.

The syntheses of butane-2,3-diacetal protected tartrate derivatives are described using continuous flow processing techniques with in-line purification and I.R. analytical protocols.

Lipid Based Aqueous Core Nanocapsules (ACNs) for Encapsulating Hydrophillic Vinorelbine Bitartrate: Preparation, Optimization, Characterization and In vitro Safety Assessment for Intravenous Administration.

BACKGROUND: Vinorelbine bitartrate (VRL) is an antimitotic agent approved by FDA for breast cancer and non-small cell lung cancer (NSCLC) in many countries. However, high aqueous solubility and thermo degradable nature of VRL limited the availability of marketed dosage forms. OBJECTIVES: The current work is focused on the development of lipid based aqueous core nanocapsules which can encapsulate the hydrophilic VRL in the aqueous core of nanocapsules protected with a lipidic shell which will further provide a sustained release. METHODS: The ACNs were prepared by double emulsification technique followed by solvent evaporation. Box Behnken Design was utilized to optimize the formulation and process variables. Thirteen batches were generated utilizing lipid concentration, surfactant concentration and homogenizer speed as dependent variables (at three levels) and particle size and encapsulation efficiency as critical quality attributes. The ACNs were characterized for particle size, zeta potential, polydispersity index (PDI), entrapment efficiency, morphology by Transmission Electron Microscopy (TEM) and in vitro release. The ACNs were further evaluated for safety against intravenous administration by haemocompatibility studies. RESULTS: Results demonstrated that lipidic nanocapsules enhanced the entrapment efficiency of VRL up to 78%. Transmission Electron Microscopy revealed spherical shape of ACNs with core-shell structure. The GMS-VRL-ACNs showed that release followed Korsemeyer peppas kinetics suggesting Fickian diffusion. Moreover, the compliance towards haemocompatibility studies depicted the safety of prepared nanocapsules against intravenous administration. CONCLUSION: ACNs were found to be promising in encapsulating high aqueous soluble anticancer drugs with enhanced entrapment and safety towards intravenous administration.

Solving manufacturing problems for L-carnitine-L-tartrate to improve the likelihood of successful product scale-up.

L-carnitine-L-tartrate, a non-essential amino acid, is hygroscopic. This causes a problem in tablet production due to pronounced adhesion of tablets to punches. A 33 full factorial design was adopted to suggest a tablet formulation. Three adsorbents were suggested (Aerosil 200, Aerosil R972, talc) to reduce stickiness at three concentrations (1, 3 and 5 %), and three fillers (mannitol, Avicel PH 101, Dibasic calcium phosphate) were chosen to prepare 27 formulations. Micromeritic properties of formulations were studied, and tablets were prepared by wet granulation. Absence of picking, sticking or capping, recording of sufficient hardness, acceptable friability and tablet ejection force indicated formulation success. The resulting formulation prepared using Avicel PH 101 and 1 % Aerosil 200 was submitted to further investigation in order to choose the most suitable compression conditions using a 33 full factorial design. Variables included compression force, tableting rate and magnesium stearate (lubricant) concentration. The formulation prepared at compression force of 25 kN, using 2 % magnesium stearate, at a production rate of 30 tablets/ minute, was found to be the most appropriate scale up candidate.

Facile synthesis of enantiopure chiral molecular rectangles exhibiting induced circular dichroism.

[structure: see text] The facile syntheses of enantiopure molecular rectangles using 1,8-bis(trans-Pt(PEt(3))(2)(NO(3)))anthracene and optically pure d- or l-tartrate are reported in high yields. These self-assembled macrocycles are unique examples where the phenomenon of induced chiral dichroism (ICD) has been observed in chiral metallosupramolecular assemblies.

Highly stable cyclic dimers based on non-covalent interactions.

Highly stable cyclic dimers have been assembled through a combination of non-covalent interactions, including multiple hydrogen bonding, parallel stacking and hydrophobic shielding.

Chemometrics Tools in Detection and Quantitation of the Main Impurities Present in Aspirin/Dipyridamole Extended-Release Capsules.

Aspirin (ASP) and dipyridamole (DIP) in combination is widely used in the prevention of secondary events after stroke and transient ischemic attack. Salicylic acid is a well-known impurity of ASP, and the DIP extended-release formulation may contain ester impurities originating from the reaction with tartaric acid. UV spectral data analysis of the active ingredients in the presence of their main impurities is presented using multivariate approaches. Four chemometric-assisted spectrophotometric methods, namely, partial least-squares, concentration residuals augmented classical least-squares (CRACLS), multivariate curve resolution (MCR) alternating least-squares (ALS), and artificial neural networks, were developed and validated. The quantitative analyses of all the proposed calibrations were compared by percentage recoveries, root mean square error of prediction, and standard error of prediction. In addition, r(2) values between the pure and estimated spectral profiles were used to evaluate the qualitative analysis of CRACLS and MCR-ALS. The lowest error was obtained by the CRACLS model, whereas the best correlation was achieved using MCR-ALS. The four multivariate calibration methods could successfully be applied for the extended-release formulation analysis. The application results were also validated by analysis of the stored dosage-form solution, which showed a susceptibility of DIP esterification in the extended-release formulation. Statistical comparison between the proposed and official methods showed no significant difference.

Dicaffeoyltartaric acid analogues inhibit human immunodeficiency virus type 1 (HIV-1) integrase and HIV-1 replication at nontoxic concentrations.

The human immunodeficiency virus type 1 (HIV-1) is a major health problem worldwide. In this study, 17 analogues of L-chicoric acid, a potent inhibitor of HIV integrase, were studied. Of these analogues, five submicromolar inhibitors of integrase were discovered and 13 compounds with activity against integrase at less than 10 microM were identified. Six demonstrated greater than 10-fold selectivity for HIV replication over cellular toxicity. Ten analogues inhibited HIV replication at nontoxic concentrations. Alteration of the linkages between the two bis-catechol rings, including the use of amides, mixed amide esters, cholate, and alkyl bridges, was explored. Amides were as active as esters but were more toxic in tissue culture. Alkyl and cholate bridges were significantly less potent against HIV-1 integrase in vitro and were inactive against HIV-1 replication. Two amino acid derivates and one digalloylderivative of L-chicoric acid (L-CA) showed improved selectivity over L-CA against integration in cell culture. These data suggest that in addition to the bis-catechols and free carboxylic acid groups reported previously, polar linkages are important constituents for optimal activity against HIV-1 integrase and that new derivatives can be developed with increased specificity for integration over HIV entry in vivo.

Catalytic asymmetric synthesis of a nitrogen analogue of dialkyl tartrate by direct mannich reaction under phase-transfer conditions.

[reaction: see text] Phase-transfer-catalyzed direct Mannich reaction of glycinate Schiff base 3 with alpha-imino ester 4 has been accomplished with high enantioselectivity by the utilization of N-spiro C(2)-symmetric chiral quaternary ammonium bromide 2 as a catalyst. This methodology enables the catalytic asymmetric synthesis of differentially protected 3-aminoaspartate, a nitrogen analogue of dialkyl tartrate. The product (syn-5) was converted into a precursor (6) of streptolidine lactam.