41653-96-7

We reported the synthesis of (S)-pregabalin in a five-step sequence with 20% overall yield. As a modification of the previously developed route, a Michael addition between CH3NO2 and chiral oxaoxazolidinone was employed as a key operation for introducing the methyleneamino group, which allowed avoiding the use of toxic cyanide reagent and led to enantiomerically pure product (>99% ee) after the recrystallization in appropriate solvent.

Dehydrogenative transformations of alkyl chains to alkenes through methylene carbon-hydrogen (C–H) activation remain a substantial challenge. We report two classes of pyridine-pyridone ligands that enable divergent dehydrogenation reactions through palladium-catalyzed b-methylene C–H activation of carboxylic acids, leading to the direct syntheses of a,b-unsaturated carboxylic acids or g-alkylidene butenolides. The directed nature of this pair of reactions allows chemoselective dehydrogenation of carboxylic acids in the presence of other enolizable functionalities such as ketones, providing chemoselectivity that is not possible by means of existing carbonyl desaturation protocols. Product inhibition is overcome through ligand-promoted preferential activation of C(sp3)–H bonds rather than C(sp2)–H bonds or a sequence of dehydrogenation and vinyl C–H alkynylation. The dehydrogenation reaction is compatible with molecular oxygen as the terminal oxidant.

The invention provides a synthesis method of a pregabalin intermediate, namely 3-nitromethylene-5-methyl-ethyl hexanoate. The synthesis method comprises the following steps: (1) reacting isovaleraldehyde with malonic acid in a choline chloride-urea eutectic solvent to obtain 5-methyl-2-hexenoic acid; (2) reacting the 5-methyl-2-hexenoic acid with absolute ethyl alcohol in a choline chloride-methanesulfonic acid eutectic solvent to obtain 5-methyl-2- ethyl hexanoate; and (3) reacting the 5-methyl-2- ethyl hexanoate with nitromethane in a choline chloride-urea eutectic solvent to obtain the 3-nitromethylene-5-methyl- ethyl hexanoate. The method does not need an organic solvent, is green, low in toxicity, environment-friendly, simple to operate, simple in post-treatment, high in yield and lowin cost, and is a green and efficient synthesis method for synthesizing the pregabalin intermediate.

The invention discloses a method for preparing 5-methyl-2-hexenoic acid. The method is characterized in that isovaleraldehyde and malonic acid undergo a Knoevenagel condensation reaction and a decarboxylation reaction with KF/K2CO3/gamma-Al2O3 as a catalyst in order to obtain the 5-methyl-2-hexenoic acid. The 5-methyl-2-hexenoic acid product produced through the method by using the isovaleraldehyde and malonic acid as raw materials and the KF/K2CO3/gamma-Al2O3 compound as the catalyst has a yield of 93% or above and a purity of 99.7% or above; the KF/K2CO3/gamma-Al2O3 compound is inexpensive,has no toxic or side effects, and can be recycled, so the input cost of the catalyst is reduced; and the method has the advantages of simple synthesis route, good reproducibility, and easiness in industrial production enforcement of the 5-methyl-2-hexenoic acid.

The invention belongs to the technical field of medicine, and more specifically relates to a phosphodiesterase 9 (PDE9) inhibitor represented by formula I, and pharmaceutically acceptable salts, solvates, polymorphic substances, and isomers thereof, and also relates to medicinal preparations, and pharmaceutical compositions of the above compounds, and applications of the medicinal preparations andpharmaceutical compositions. The compounds and the pharmaceutically acceptable salts, solvates, polymorphic substances, and isomers can be used in treatment of phosphodiesterase 9 (PDE9) abnormal expression mediated related diseases.

The Cs2CO3-mediated annulations ("Deslongchamps annulations") of three spirocyclic benzoquinone monoketals 5b-d with an ester or acyl substituent at C-2 to two tert-butyl esters of λδ-unsaturated β-ketocarboxyl acids ("Nazarov reagents" 2a,b) were monitored 1H NMR spectroscopically. This revealed that a primary product, by all likelihood the Michael adduct, forms fast and prior to the appearance of the Deslongchamps adduct. These primary products form reversibly. This was proved by two crossover and four scavenging experiments. Therein, components already incorporat.

An enantioselective sulfa-Michael-cyclization reaction was developed for the synthesis of 1,5-benzothiazepines with versatile pharmacological activities. The reaction between 2-aminothiophenol and α,β-unsaturated pyrazoleamides gave direct access to N?H-free 1,5-benzothiazepines in the presence of a chiral N,N′-dioxide/Yb(OTf)3complex. Excellent enantioselectivities (up to 96 % ee) and high yields (up to 99 %) were obtained for a broad range of substrates under mild reaction conditions. This method provided a facile approach to the antidepressant drug (R)-(?)-Thiazesim.

Carboxylating enoyl-thioester reductases (ECRs) are a recently discovered class of enzymes. They catalyze the highly efficient addition of CO2 to the double bond of α,β-unsaturated CoA-thioesters and serve two biological functions. In primary metabolism of many bacteria they produce ethylmalonyl-CoA during assimilation of the central metabolite acetyl-CoA. In secondary metabolism they provide distinct α-carboxyl-acyl-thioesters to vary the backbone of numerous polyketide natural products. Different ECRs were systematically assessed with a diverse library of potential substrates. We identified three active site residues that distinguish ECRs restricted to C4 and C5-enoyl-CoAs from highly promiscuous ECRs and successfully engineered a selected ECR as proof-of-principle. This study defines the molecular basis of ECR reactivity, allowing for predicting and manipulating a key reaction in natural product diversification.

We have explored in this work the conjugate addition of diethylaluminum cyanide (Nagata's reagent) to an N-enoyl system bearing the (R)-4-phenyl-2- oxazolidinone chiral auxiliary. Since this method provided a practical synthesis of γ-amino acids, we report the conjugate addition of diethylaluminum cyanide as the key step in the synthesis of (S)-pregabalin 1 in a five-step sequence of reactions from commercially available starting materials.

This contribution reports the preparation and use of a new immobilized catalyst, PS-DABCOF (9), which has been specifically designed to access for the first time the efficient β-azidation of α,β-unsaturated carboxylic acids.

The invention relates to a process for preparing a compound of formula (I): wherein said process comprises hydrogenation of a compound of formula (II); under alkaline conditions, wherein R represents hydrogen or a labile group capable of being converted to hydrogen. The invention also relates to intermediates used in said process, to the use of said intermediates in the preparation of pregabalin and to a process for resolving racemic compounds of formula (I).

The invention relates to a process for preparing a compound of formula (I): wherein said process comprises hydrogenation of a compound of formula (II): under alkaline conditions, wherein R represents hydrogen or a labile group capable of being converted to hydrogen. The invention also relates to intermediates used in said process, to the use of said intermediates in the preparation of pregabalin and to a process for resolving racemic compounds of formula (I).

The present invention relates to a process for preparing aldehydes by reacting an α,β-unsaturated carboxylic acid or a salt thereof with carbon monoxide and hydrogen in the presence of a catalyst comprising at least one complex of a metal of transition group VIII of the Periodic Table of the Elements with at least one compound of the formula (I), where Pn is pnicogen; W is a divalent bridging group having from 1 to 8 bridge atoms between the flanking bonds; R1 is a functional group capable of forming at least one intermolecular, noncovalent bond with the —X(═O)OH group of the compound of the formula (I); R2, R3 are each in each case optionally substituted alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl or together with the pnicogen atom and together with the groups Y2 and Y3 if present form an optionally fused and optionally substituted 5- to 8-membered heterocycle; a, b and c are each 0 or 1; and Y1,2,3 are each, independently of one another, O, S, NRa or SiRbRc, where Ra,b,c are each H or in each case optionally substituted alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl; and the use of the above-described catalyst for the decarboxylative hydroformylation of α,β-unsaturated carboxylic acids.

(Chemical Equation Presented) Head 'em up, move 'em out, aldehyde! A catalytic transformation of α,β-unsaturated carboxylic acids into aldehydes through a hydroformylation-decarboxylation process has been developed (see scheme; Do = donor ligand, FG1 and FG2 = complementary functional groups). The reaction proceeds at mild conditions, tolerates many functional groups, and liberates CO2 as the only stoichiometric by-product.

(Chemical Equation Presented) Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe)2]2 and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1,2-disubstituted as well as trisubstituted alkenes were achieved with enantioselectivities >90% ee for each substrate class. Cyclization of substrates with Z-alkene isomers proceeded much more efficiently than substrates with E-alkene isomers. This further enabled the highly stereoselective intramolecular alkylation of certain substrates containing Z/E-alkene mixtures via a Rh-catalyzed alkene isomerization with preferential cyclization of the Z-isomer.

The present invention encompasses novel intermediates of pregabalin, namely 3 -cyano-5 -methyl hexanamide (28) and 3-(amino methyl)-5 methyl hexanamide (29), and processes for their preparation. The invention also encompasses a process for converting the novel pregabalin intermediates into pregabalin, Formula (I): The present invention further provides a cost effective method for the synthesis of (S)-pregabalin, which involves the recovery of mandelic acid and tartaric acid used in the resolution process and recycling them, increasing the yields of the final product formed, which substantially reduced the cost of the production.

Here we studied the homologation of leucic and phenyl lactic acid via Wolff-rearrangement of their diazoketones to the corresponding β-hydroxy acids. This reaction requires distinct conditions to that of their amino acid analogues. The choice of the Oα-substituent can selectively direct the reaction to α-unsubstituted β-hydroxy carboxamides or (E)-α,β-unsaturated carboxamides and offers a new route from α-hydroxy acids to such compounds.

A promoted SmI2 direct reaction of dibromoacetic acid with different aldehydes, followed by an elimination reaction also promoted by samarium diiodide, affords (E)-α,β-unsaturated carboxylic acids 2 with total stereoselectivity. A mechanism to explain this transformation is proposed.

The Rodionov reaction of 49 available aliphatic and aromatic aldehydes with malonic acid and ammonium acetate in alcoholic medium, resulting in formation of β-amino acids, propenoic, and ylidenemalonic acids, was studied. Certain regioselectivity regularities of the reaction were revealed. Among the variety of ketones studied, cyclohexanone is the only whose reaction yields a β-amino acid. Unusual dehydrofluorination of 6-chloro-2-fluorocinnamic acid under the Rodionov reaction was discovered. 2005 Pleiades Publishing, Inc.

The synthesis of cis- and trans-aziridine hydroxamic acid derivatives as MMP inhibitors is described using enantio- and diastereoselective methods for the formation of trisubstituted aziridines. Their preliminary inhibitory activity is reported and discus

With the aim of characterizing the active site of the neutral endopeptidase and especially its putative S1 subsite, two series of new thiol inhibitors designed to interact with the S1, S'1, and S'2 subsites of the enzyme have been synthesized.These molecules correspond to the general formula HSCH(R1)CH(R2)CONHCH(R3)COOH (series I) and HSCH(R1)CH(R2)CONHCH(R3)CONHCH(R4)COOH (series II).Due to the synthetic pathway used, these inhibitors were obtained as mixtures of four stereoisomers.HPLC separation of the stereoisomers of 17 HSCHCH(CH2Ph)CONHCH(CH3)COOH allowed the stereochemical dependence of the inhibitory potency to be determined.The most active isomer 17b (IC50 = 3.6 nM) is assumed to have the S,S,S stereochemistry as deduced from both NMR and HPLC data.Although none of the inhibitors obtained were significantly more active than thiorphan, HSCH2CH(CH2Ph)CONHCH2COOH (IC50 = 4 nM), which interacts only with the S'1 and S'2 subsites of NEP, their enhanced hydrophobicity is expected to improve their pharmacokinetic properties.All these compounds displayed low affinities for ACE (IC50S > 1 μM).The determination of the IC50S of two inhibitors of series II for NEP and for a mutated enzyme in which Arg102 was replaced by Glu102 allowed their mode of binding to the active site of NEP to be characterized.The R2 and R3 chains fit the S'1-S'2 subsites, while the R4 group is probably located outside the active site.Taken together these results indicate that the R1 chain of these inhibitors creates no additional stabilizing interactions with the active site of NEP.Two hypotheses may account for this: there is no hydrophophobic S1 subsite in NEP or the inhibitors have structures which are too constrained for optimized interactions with the active site.

Carboxylic acids are manufactured by reaction of methyl ketones with hypochlorites in the presence of bromine, iodine, haloamides, and/or polymerization inhibitors. The products are starting materials for the manufacture of dyes, plant protection agents, tanning agents, pickling agents, bates, vulcanizing agents and scents.