176019-05-9

The GE81112 complex has garnered much interest due to its broad antimicrobial properties and unique ability to inhibit bacterial translation initiation. Herein we report the use of a chemoenzymatic strategy to complete the first total synthesis of GE81112 B1. By pairing iron and α-ketoglutarate dependent hydroxylases found in GE81112 biosynthesis with traditional synthetic methodology, we were able to access the natural product in 11 steps (longest linear sequence). Following this strategy, 10 GE81112 B1 analogues were synthesized, allowing for identification of its key pharmacophores. A key feature of our medicinal chemistry effort is the incorporation of additional biocatalytic hydroxylations in modular analogue synthesis to rapidly enable exploration of relevant chemical space.

Studies on the substrate selectivity of recombinant ferrous-iron- and 2-oxoglutarate-dependent proline hydroxylases (PHs) reveal that they can catalyse the production of dihydroxylated 5-, 6-, and 7-membered ring products, and can accept bicyclic substrates. Ring-substituted substrate analogues (such hydroxylated and fluorinated prolines) are accepted in some cases. The results highlight the considerable, as yet largely untapped, potential for amino acid hydroxylases and other 2OG oxygenases in biocatalysis.

A unified synthetic strategy for oseltamivir phosphate (tamiflu), (S)-pipecolic acid, and its 3-hydroxy derivatives from furan derived common chiral bicycloaziridino lactone synthon is described here. Key features are the short (4-steps), enantiopure, and decagram-scale synthesis of common chiral synthon from furan and its first-ever application in the total synthesis of biologically active compounds by taking the advantages of high functionalization ability of chiral synthon.

The enantioselective synthesis of 4-epi-fagomine was accomplished starting from dioxanone and Cbz-protected benyzlamine, in 4 steps, with 18% overall yield. The key feature of this synthetic approach is the tactical combination of reactions: organocatalyz

Concise total syntheses of (R)-pipecolic acid, (R)-ethyl-6-oxopipecolate, (2R,3R)-3-hydroxypipecolic acid and formal syntheses of β-(+)-conhydrine, (-)-lentiginosine, (-)-swainsonine and 1,2-di-epi-swainsonine have been accomplished starting from a common chiral synthon. The present strategy employs regioselective aziridine ring opening, Wittig olefination and RCM as the key chemical transformations.

The present invention aims to provide a method for purifying cis-5-hydroxy-2-piperidinecarboxylic acid with high purity, and a method for producing its derivative. The present invention provides a method for producing a cis-5-hydroxy-2-piperidinecarboxylic acid derivative, which method comprises a step of converting cis-5-hydroxy-2-piperidinecarboxylic acid into a compound(s) of Formula (1) and/or Formula (2) (wherein R1 represents a protective group for an amino group, and R2 represents a C1-C6 alkyl group), and a method for purifying cis-5-hydroxy-2-piperidinecarboxylic acid.

We evaluated the substrate specificities of four proline cis-selective hydroxylases toward the efficient synthesis of proline derivatives. In an initial evaluation, 15 proline-related compounds were investigated as substrates. In addition to L-proline and L-pipecolinic acid, we found that 3,4-dehydro-L-proline, L-azetidine-2-carboxylic acid, cis-3-hydroxy-L-proline, and L-thioproline were also oxygenated. Subsequently, the product structures were determined, revealing cis-3,4-epoxy-L-proline, cis-3-hydroxy-L-azetidine-2-carboxylic acid, and 2,3-cis-3,4-cis-3,4-dihydroxy-L-proline.

A convenient synthesis of (2S,3S)-3-hydroxypipecolic acid starting from cheap and abundant l-(+)-tartaric acid has been achieved. The strategy employs selective ester reduction and reductive lactamization as key steps.

The γ-butenolide obtained from an organocatalyzed, direct vinylogous aldol reaction of γ-crotonolactone and benzaldehyde serves as the key starting material in the expedient synthesis of a 3-hydroxy-2-phenyl piperidine intermediate which is converted to the target 2,3-disubstituted piperidines.

Stereoselective routes to cis-(2S,3R)-3-hydroxypipecolic acid and two enantiomeric cis-2-hydroxymethyl-3-hydroxypiperidine derivatives from a common precursor have been developed, which featured stereocontrolled vinylation of a -chiral aldehyde and ring-closing metathesis as key steps. Georg Thieme Verlag Stuttgart. New York.

Due to their diverse regio- and stereoselectivities, proline hydroxylases provide a straightforward access to hydroxprolines and other hydroxylated cylic amino acids, valuable chiral building blocks for chemical synthesis, which are often not available at reasonable expense by classical chemical synthesis. As yet, the application of proline hydroxylases is limited to a sophisticated industrial process for the production of two hydroxyproline isomers. This is mainly due to difficulties in their heterologues expression, their limited in vitro stability and complex product purification procedures. Here we describe a facile method for the production of cis-3-, cis-4- and trans-4-proline hydroxylase, and their application for the regio- and stereoselective hydroxylation of L-proline and its six-membered ring homologue l-pipecolic acid. Since in vitro catalysis with these enzymes is not very efficient and conversions are restricted to the milligram scale, an in vivo procedure was established, which allowed a quantitative conversion of 6 mM l-proline in shake flask cultures. After facile product purification via ion exchange chromatography, hydroxyprolines were isolated in yields of 35-61% (175-305 mg per flask). L-Pipecolic acid was converted with the isolated enzymes to prove the selectivities of the reactions. In transformations with optimized iron(II) concentration, conversions of 17-68% to hydroxylated products were achieved. The regio- and stereochemistry of the products was determined by NMR techniques. To demonstrate the applicability of the preparative in vivo approach for non-physiological substrates, L-pipecolic acid was converted with an E. coli strain producing trans-4-proline hydroxylase to trans-5-hydroxy-L-pipecolic acid in 61% yield. Thus, a synthetically valuable group of biocatalysts was made readily accessible for application in the laboratory without a need for special equipment or considerable development effort.

The GE81112 tetrapeptides (1-3) represent a structurally unique class of antibiotics, acting as specific inhibitors of prokaryotic protein synthesis. Here we report the cloning and sequencing of the GE81112 biosynthetic gene cluster from Streptomyces sp. L-49973 and the development of a genetic manipulation system for Streptomyces sp. L-49973. The biosynthetic gene cluster for the tetrapeptide antibiotic GE81112 (getA-N) was identified within a 61.7-kb region comprising 29 open reading frames (open reading frames), 14 of which were assigned to the biosynthetic gene cluster. Sequence analysis revealed the GE81112 cluster to consist of six nonribosomal peptide synthetase (NRPS) genes encoding incomplete di-domain NRPS modules and a single free standing NRPS domain as well as genes encoding other biosynthetic and modifying proteins. The involvement of the cloned gene cluster in GE81112 biosynthesis was confirmed by inactivating the NRPS gene getE resulting in a GE81112 production abolished mutant. In addition, we characterized the NRPS A-domains from the pathway by expression in Escherichia coli and in vitro enzymatic assays. The previously unknown stereochemistry of most chiral centers in GE81112 was established from a combined chemical and biosynthetic approach. Taken together, these findings have allowed us to propose a rational model for GE81112 biosynthesis. The results further open the door to developing new derivatives of these promising antibiotic compounds by genetic engineering.

"Chemical Equation Presented" Stereoselective syntheses of L-pipecolic acid and (2S,3S)3-hydroxypipecolic acid were achieved from a chiral AMmino-2-phenyl-l,2-dihydropyridine intermediate. The 3-hydroxy substituent of the latter amino acid was introduced, by hetero-Diels-Alder reaction of singlet, oxygen with the 1,2-dihydropyridine.

(Chemical Equation Presentation) Facile syntheses of enantiopure trans- and cis-3-hydroxypiperidine derivatives and 3-hydroxypipecolic acids are reported, featuring Rh-catalyzed cyclohydrocarbonylation through common intermediates. A diaxial conformation in a 2,3-disubstituted N-Boc-piperidinyl structure is revealed by an X-ray crystallographic analysis.

Stereoselective synthesis of cis-3-hydroxypipecolic acid was achieved via chirality transfer in the SmI2-mediated cyclization reactions of aldehydo β-aminovinyl sulfoxides.

A very short route to 2-phenylpiperidin-3-ol derivatives and 3-hydroxypipecolic acids is described. The approach uses two key steps: a one-pot reduction/Grignard addition sequence applied to alkyl proline esters and a ring expansion applied to the corresp

(Chemical Equation Presented) The first chiron approach from D-glucose for the total synthesis of (2S,3R)-3-hydroxypipecolic acid (-)-1a and (2R,3R)-3-hydroxy-2-hydroxymethylpiperidine (-)-2a is reported. The synthetic pathway involves conversion of D-glucose into 3-azidopentodialdose (5) followed by the Wittig olefination and reduction to give the piperidine ring skeleton (8) with a sugar appendage that on cleavage of an anomeric carbon followed by oxidation gives (-)-1a which on reduction affords (-)-2a.

An efficient stereoselective synthesis of (2S,3S)-3-hydroxypipecolic acid was achieved from (S)-glutamic acid via the furylation of an N-protected 6-hydroxy-2-piperidinone using furan as a nucleophile and the oxidation of the furyl group to a carboxylic group as the key steps.

We have synthesized 3-hydroxy- and 3,4,5-trihydroxypipecolic acid derivatives corresponding to 5-aza derivatives of uronic acids and evaluated their inhibitory activities against various glycosidases including β-glucuronidase. Compounds 4 and 5 were chosen as common intermediates for the synthesis of 3,4,5-trihydroxypipecolic acids and 3-hydroxypipecolic acids as well as for 3-hydroxybaikiain, a unique natural product isolated from a toxic mushroom. Cross aldol reaction of N-Boc-allylglycine derivative with acrolein followed by the ring-closing metathesis gave 4 and 5 as a mixture of diastereomers which could be separated by silica gel column chromatography. By employing lipase-catalyzed kinetic resolution, the synthesis of both l- and d-isomers of 3,4,5-trihydroxy- and 3-hydroxypipecolic acids was achieved. None of the compounds tested showed inhibitory activity against α- and β-glucosidases. On the other hand, l-23 and l-29 were found to have potent inhibitory activity against β-glucuronidase. In addition, it is interesting that some uronic-type azasugar derivatives showed moderate inhibitory activities against β-N-acetylglucosaminidase.

A highly practicable synthesis of both enantiomers of 3-hydroxypipecolic acid derivatives 1, 2, 3, 4 is described. Screening of these molecules for glycosidase inhibition has been examined. Compound 3 was shown to be a potent inhibitor of β-N-acetylglucosaminidase as well as Escherichia coli β-glucuronidase.

A short and efficient stereoselective synthetic approach toward substituted piperidines, involving (2S,3S)-3-hydroxypipecolic acid 1, (2R,3S)-3-hydroxypipecolic acid 3, and their acid-reduced analogs 2 and 4, has been developed. The requisite anti- and sy

A stereoselective total synthesis of (2R,3S)-3-hydroxypipecolic acid starting from an enantiomerically pure α-amino alcohol is reported. The synthesis involved a regioselective mesylation and subsequent cyclisation as key steps.

An efficient stereoselective syntheses of (2S,3S)-3-hydroxypipecolic acid and (2R,3S)-2-hydroxymethylpiperidin-3-ol were achieved from p-anisaldehyde via the regioselective and diastereoselective introduction of an N-protected amine group using chlorosulf

(Chemical Equation Presented). Both the enantiomers of trans-3- hydroxypipecolic acid have been synthesized employing the Sharpless asymmetric dihydroxylation and epoxidation as the key steps starting from a commercially available starting material 1,4-bu

A concise enantioselective synthesis of (2S,3S)-3-hydroxypipecolic acid 1 starting from 1,4-butanediol using Sharpless asymmetric dihydroxylation and the regioselective nucleophilic opening of a cyclic sulfate as the key steps is described. A concise enan

The invention provides compounds of the formula I wherein the substitutents are as described herein. Further provided are methods of using such compounds for the treatment of nuclear hormone receptor-associated conditions, such as age related diseases, for example sarcopenia, and also provided are pharmaceutical compositions containing such compounds.

The enantioselective synthesis of trans-(2R,3R)-3-hydroxypipecolic acid 1b is presented, starting from O-protected methyl mandelate as chiral source. The synthesis involved a regioselective intramolecular nucleophilic substitution of an azido epoxide as t

An efficient enzymatic resolution of racemic cis-β-hydroxypipecolic acid is described affording both the (2S,3R) and (2R,3S) protected amino acids in good yield and high enantiomeric ratios. (C) 2000 Elsevier Science Ltd.

Asymmetric syntheses of (2R,3R) and (2R,3S)-3-hydroxypipecolic acids are reported featuring a key diastereoselective addition of Buchi's Grignard reagent to the chiral serinal L-5. Based on conformational analysis, a stereocontrolled reduction of piperidi

A variety of chiral β-hydroxy-α-amino acids and derivatives thereof can be synthesized enantioselectively using the aldol reaction of an aldehyde, the gIycinate 1 and the cinchonidinederived catalyst 2, as indicated in Schemes 1 and 2 and Table 1.

Substrate selectivities of microbial proline 4-hydroxylase and proline 3-hydroxylases, all of which were purified from recombinant Escherichia coli, were investigated. L-2-Azetidine carboxylate, 3,4-dehydro-L-proline and L- pipecolinic acid were hydroxylated by those enzymes in regio- and stereospecific manner.

The differential oxidation of five and six-membered endocyclic enecarbamates was investigated employing m-CPBA, DMD, as well as enantioselectivc protocols such as the Kochi-Jacobsen-Katsuki's epoxidation and the Sharpless dihydroxylation. By this strategy the syntheses of β- hydroxyprolines and β-hydroxypipecolic acids were accomplished, X-Ray crystallographic analysis of the trans-β-hydroxypipecolic acid was instrumental to solve structural assignment conflicts.

The asymmetric syntheses of 2(R), 3(R)- and 2(S), 3(S)-β- hydroxypipecolic acids are described, including the determination of the absolute stereochemistry of the β-hydroxypipecolic acid moiety of tetrazomine.

trans-β-Hydroxypipecolic acids of both L- and D-series, L-1 and D-1, have been straightforwardly prepared in 14% and 15% yields, respectively, starting from glyceraldehyde imines D-7 and L-7 as useful three-carbon chirons. The key feature of these parallel syntheses lies on the highly diastereoselective character of the initial coupling manoeuver between silyloxy furan TBSOF and imines 7, which ultimately accounts for the relative, and hence absolute configuration of the target pipecolic acids.

Three protected 3-substituted pipecolic acid analogs were prepared as constrained chimeric amino acid building blocks. The concise synthetic route enables the synthesis of other derivatives with sidechain functionality of amino acids as well.

The enantioselective synthesis of both enantiomers of trans-3-hydroxypipecolic acid are described from a prochiral starting material: the methyl 3-oxo-7-methyloct-6-enoate.The stereocenters of the piperidine ring are created by enantioselective hydrogenation of the β-ketoester and by diastereoselective electrophilic amination of the β-hydroxyester enolate. (2R,3R)-3-Hydroxypipecolic acid methyl ester is the precursor for the synthesis of (-)-swainsonine. - Keywords: piperidine; indolizidine; chiral ruthenium complex; electrophilic amination.

The first syntheses of enantiomerically pure (2R, 3R) and (2S, 3S) 3-hydroxypipecolic acids 1 and 2 respectively, have been achieved from methyl 7-methyl-3-oxo-6-octenoate. Key steps involved asymmetric hydrogenation and electrophilic amination.

Bicyclic oxazolidine 6, a potential precursor for the synthesis of enantiopure piperidines and indolizidines, was synthesized from (R)-phenylglycinol. A stereoselective addition of cyanide anion on this compound afforded ultimately (2S,3S)-3-hydroxypipecolic acid 9.

Except for structurally similar small amino acids, such as alanine, β-alanine, and serine, compounds acting as glycine-receptor agonists are an unknown class of pharmacological agents.To investigate the potential of small, substituted heterocycles to act as glycine agonists, we have evaluated the similarities between glycine and a series of hydroxy- and amino-substituted pyrazoles and isoxazoles through complementary molecular modeling techniques.Using a "scorecard approach" to determine the overall similarity of projected agonist structures to glycine, we prioritized synthesis and subsequently prepared several novel derivatives.The biological activity of these compounds was compared to that of glycine by using a strychnine-mediated glycine receptor binding assay.Despite the close similarity in the calculated parameters when compared to glycine, no significant receptor-binding activity was observed for the targeted analogues.These results illustrate the structurally exacting nature of the glycine receptor.

-