- Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of N-(2-Hydroxyethyl)amides into 2-Oxazolines
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A metal-free, biomimetic catalytic protocol for the cyclization of N-(2-hydroxyethyl)amides to the corresponding 2-oxazolines (4,5-dihydrooxazoles), promoted by the 1,3,5,2,4,6-triazatriphosphorine (TAP)-derived organocatalyst tris(o-phenylenedioxy)cyclotriphosphazene (TAP-1) has been developed. This approach requires less precatalyst compared to the reported relevant systems, with respect to the phosphorus atom (the maximum turnover number (TON) ～30), and exhibits a broader substrate scope and higher functional-group tolerance, providing the functionalized 2-oxazolines with retention of the configuration at the C(4) stereogenic center of the 2-oxazolines. Widely accessible β-amino alcohols can be used in this approach, and the cyclization of N-(2-hydroxyethyl)amides provides the desired 2-oxazolines in up to 99% yield. The mechanism of the reaction was studied by monitoring the reaction using spectral and analytical methods, whereby an 18O-labeling experiment furnished valuable insights. The initial step involves a stoichiometric reaction between the substrate and TAP-1, which leads to the in situ generation of the catalyst, a catechol cyclic phosphate, as well as to a pyrocatechol phosphate and two possible active intermediates. The dehydrative cyclization was also successfully conducted on the gram scale.
- Soleymani Movahed, Farzaneh,Foo, Siong Wan,Mori, Shogo,Ogawa, Saeko,Saito, Susumu
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p. 243 - 257
(2021/12/17)
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- Retention of chirality of 5-membered alicyclic α-amino acids bearing N-(2-phenyl)benzoyl group in photoinduced decarboxylative intermolecular radical addition to acrylonitrile
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Photoinduced decarboxylative radical additions of 5-membered alicyclic α-amino acids bearing a (2-phenyl)benzoyl protective group to acrylonitrile under mild organic photoredox catalysis conditions furnished γ-amino acid derivatives with high retention of chirality via the memory of chirality (MOC) strategy. The retention of chirality in the photoinduced decarboxylation was strongly dependent on the structure of the alicyclic α-amino acids and alkenes. To the best of our knowledge, this is the first example of the decarboxylative intermolecular radical addition to alkenes with retention of chirality at the position of radical generation using the MOC strategy.
- Ozaki, Yui,Yamada, Tomoaki,Mizuno, Taisei,Osaka, Kazuyuki,Yamawaki, Mugen,Maeda, Hajime,Morita, Toshio,Yoshimi, Yasuharu
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- Synthesis and evaluation of in vivo anti-hypothermic effect of all stereoisomers of the thyrotropin-releasing hormone mimetic: Rovatirelin Hydrate
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We discovered the orally active thyrotropin-releasing hormone (TRH) mimetic: (4S,5S)-5-methyl-N-{(2S)-1-[(2R)-2-methylpyrrolidin-1-yl]-1-oxo-3-(1,3-thiazol-4-yl)propan-2-yl}-2-oxo-1,3-oxazolidine-4-carboxamide 1 (rovatirelin). The central nervous system (CNS) effect of rovatirelin after intravenous (iv) administration is 100-fold higher than that of TRH. As 1 has four asymmetric carbons in its molecule, there are 16 stereoisomers. We synthesized and evaluated the anti-hypothermic effect of all stereoisomers of 1, which has the (4S),(5S),(2S),(2R) configuration from the N-terminus to the C-terminus, in order to clarify the structure?activity relationship (SAR) of stereoisomers. The (4R),(5R),(2R),(2S)-isomer 16 did not show any anti-hypothermic effect. Only the (4S),(5S),(2S),(2S)-isomer 10, which has the (2S)-2-methylpyrrolidine moiety at the C-terminus showed the anti-hypothermic effect similar to 1. Stereoisomers, which have the (5R) configuration of the oxazolidinone at the N-terminus and the (2R) configuration at the middle-part, showed a much lower anti-hypothermic effect than that of 1. On the other hand, stereoisomers, which have the (4R) configuration of the oxazolidinone at the N-terminus or the (2S) configuration of the C-terminus, have little influence on the anti-hypothermic effect.
- Kobayashi, Naotake,Sato, Norihito,Sugita, Katsuji,Takahashi, Kouji,Sugawara, Tamio,Tada, Yukio,Yoshikawa, Takayoshi
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- Modulating the Serotonin Receptor Spectrum of Pulicatin Natural Products
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Serotonin (5-HT) receptors are important in health and disease, but the existence of 14 subtypes necessitates selective ligands. Previously, the pulicatins were identified as ligands that specifically bound to the subtype 5-HT2B in the 500 nM to 10 μM range and that exhibited in vitro effects on cultured mouse neurons. Here, we examined the structure-activity relationship of 30 synthetic and natural pulicatin derivatives using binding, receptor functionality, and in vivo assays. The results reveal the 2-arylthiazoline scaffold as a tunable serotonin receptor-targeting pharmacophore. Tests in mice show potential antiseizure and antinociceptive activities at high doses without motor impairment.
- Lin, Zhenjian,Smith, Misty D.,Concepcion, Gisela P.,Haygood, Margo G.,Olivera, Baldomero M.,Light, Alan,Schmidt, Eric W.
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p. 2360 - 2370
(2017/09/01)
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- Synthesis of 2-oxazolines by in situ desilylation and cyclodehydration of β-hydroxyamides
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A powerful method for the synthesis of 2-oxazolines from silyl-protected β-hydroxyamides is reported. Using diethylaminosulfur trifluoride (DAST) or its tetrafluoroborate salt (XtalFluor-E), silyl-protected β-amidoalcohols can be in situ deprotected and d
- Brandst?tter, Marco,Roth, Fabian,Luedtke, Nathan W.
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- The rapid synthesis of oxazolines and their heterogeneous oxidation to oxazoles under flow conditions
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A rapid flow synthesis of oxazolines and their oxidation to the corresponding oxazoles is reported. The oxazolines are prepared at room temperature in a stereospecific manner, with inversion of stereochemistry, from β-hydroxy amides using Deoxo-Fluor. The
- Gl?ckner, Steffen,Tran, Duc N.,Ingham, Richard J.,Fenner, Sabine,Wilson, Zoe E.,Battilocchio, Claudio,Ley, Steven V.
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supporting information
p. 207 - 214
(2015/02/02)
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- ETHYNYLBENZENE DERIVATIVES
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Disclosed are compounds of formulae (I), (II), and (II)I: and pharmaceutically acceptable salts thereof, wherein the variables, R, R1, R2, R3, R101, L, D, Q, Y, X, and Z are defined herein. These compounds are useful for treating Gram-negative bacteria infections.
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Page/Page column 99-100
(2012/03/26)
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- Syntheses, structures and antibiotic activities of LpxC inhibitors based on the diacetylene scaffold
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Compounds inhibiting LpxC in the lipid A biosynthetic pathway are promising leads for novel antibiotics against multidrug-resistant Gram-negative pathogens. We report the syntheses and structural and biochemical characterizations of LpxC inhibitors based on a diphenyl-diacetylene (1,4-diphenyl-1,3-butadiyne) threonyl-hydroxamate scaffold. These studies provide a molecular interpretation for the differential antibiotic activities of compounds with a substituted distal phenyl ring as well as the absolute stereochemical requirement at the C2, but not C3, position of the threonyl group.
- Liang, Xiaofei,Lee, Chul-Jin,Chen, Xin,Chung, Hak Suk,Zeng, Daina,Raetz, Christian R.H.,Li, Yaoxian,Zhou, Pei,Toone, Eric J.
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supporting information; experimental part
p. 852 - 860
(2011/03/19)
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- Synthesis of substituted oxazoles from N-acyl-β-hydroxyamino acid derivatives
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Several N-acyl-β-hydroxyamino acids were prepared and treated with di-tert-butyl dicarbonate in the presence of 4-(dimethylamino)pyridine, followed by treatment with N,N,N′,N′-tetramethylguanidine to give the corresponding N-acyldehydroamino acids in good
- Ferreira, Paula M. T.,Monteiro, Luis S.,Pereira, Goreti
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experimental part
p. 4676 - 4683
(2009/05/27)
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- Modular phosphite-oxazoline/oxazine ligand library for asymmetrie Pd-catalyzed allylic substitution reactions: scope and limitations - origin of enantioselectivity
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A library of phosphite-oxazoline/oxazine ligands L1-L15a-h has been synthesized and screened in the Pd-catalyzed allylic substitution reactions of several substrate types. These series of ligands can be prepared efficiently from easily accessible hydroxyl amino acid derivatives. Their modular nature enables the substituents/configurations in the oxazoline/oxazine moiety, alkyl backbone chain and in the biaryl phosphite moiety to be easily and systematically varied. By carefully selecting the ligand components, therefore, high regio- and enantioselectivities (ee values up to 99%) and good activities have been achieved in a broad range of mono- and disubstituted linear hindered and unhindered liner and cyclic substrates. The NMR studies on the Pd-π-allyl intermediates provide a deeper understanding about the effect of the ligand parameters on the origin of enantioselectivity. It also indicates that the nucleophilic attack takes place predominantly at the allylic terminal carbon atom located trans to the phosphite moiety.
- Dieguez, Montserrat,Pamies, Oscar
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experimental part
p. 3653 - 3669
(2009/04/23)
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- Toward the development of chemoprevention agents. Part 1: Design, synthesis, and anti-inflammatory activities of a new class of 2,5-disubstituted-dioxacycloalkanes
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A new class of 2,5-disubstituted-dioxacycloalkanes were designed and synthesized via stereoselective synthetic method as cancer chemoprevention agents. The anti-inflammatory activities of these compounds were tested using the xylene-induced mouse ear edema model. Some of these compounds exhibited comparable or better anti-inflammatory activities than that of aspirin suggesting that they can be further developed as potential anti-inflammatory drug lead compounds. In addition, treatment of these anti-inflammatory agents did not prolong tail bleeding time in mice. The structure/activity relationships were also analyzed among these compounds.
- Gu, Keli,Bi, Lanrong,Zhao, Ming,Wang, Chao,Ju, Jingfang,Peng, Shiqi
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p. 4775 - 4799
(2008/03/14)
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- Chiral 1,4-bis-diphosphine ligands from optically active (Z)-olefines
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The catalytic asymmetric hydrogenation of prochiral ketones was carried out with Ru(II) complexes prepared from new chiral diphosphine ligands, cis-(R,R)-2,5-bis[(diarylphosphino)]-3-hexenes. These new ligands were prepared from enantiomerically pure (R,R) or (S,S)-(Z)-3-hexene-2,5 diol and enantiomeric excesses up to 85% were obtained in the reduction of 2-benzamidomethyl-3-oxobutanoate, starting material for the synthesis of 4-acetoxy-2-azetidinone.
- Cesarotti, Edoardo,Rimoldi, Isabella,Spalluto, Paola,Demartin, Francesco
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p. 1278 - 1283
(2008/03/12)
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- New Dihydroxy Bis(Oxazoline) Ligands for the Palladium-Catalyzed Asymmetric Allylic Alkylation: Experimental Investigations of the Origin of the Reversal of the Enantioselectivity
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The origin of the reversal of the enantioselectivity in the palladium-catalyzed allylic alkylation of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate anion using chiral dihydroxy bis(oxazoline) "BO" ligands derived from (1S,2S)-(+)-2-amino-1-ph
- Ait-Haddou, Hassan,Hoarau, Olivier,Cramailere, Dimitri,Pezet, Frederic,Daran, Jean-Claude,Balavoine, Gilbert G. A.
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p. 699 - 707
(2007/10/03)
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- MATERIALS AND METHODS FOR THE TREATMENT OF DIABETES, HYPERLIPIDEMIA, HYPERCHOLESTEROLEMIA, AND ATHEROSCLEROSIS
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The subject invention provides pharmaceutical compounds useful in the treatment of Type II diabetes. These compounds are advantageous because they are readily metabolized by the metabolic drug detoxification systems. Particularly, thiazolidinedione analogs that have been designed to include esters within the structure of the compounds are provided. This invention is also drawn to methods of treating disorders, such as diabetes, comprising the administration of therapeutically effective compositions comprising compounds that have been designed to be metabolized by serum or intracellular hydrolases and esterases. Pharmaceutical compositions of the ester-containing thiazolidinedione analogs are also taught.
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Page column 43
(2010/02/07)
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- Materials and methods for the treatment of diabetes, hyperlipidemia, hypercholesterolemia, and atherosclerosis
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The subject invention provides pharmaceutical compounds useful in the treatment of Type II diabetes. These compounds are advantageous because they are readily metabolized by the metabolic drug detoxification systems. Particularly, thiazolidinedione analogs that have been designed to include esters within the structure of the compounds are provided. This invention is also drawn to methods of treating disorders, such as diabetes, comprising the administration of therapeutically effective compositions comprising compounds that have been designed to be metabolized by serum or intracellular hydrolases and esterases. Pharmaceutical compositions of the ester-containing thiazolidinedione analogs are also taught.
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- Nitrate esters in the generation of amino acid radicals
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Nitrate esters, prepared by treatment of β-hydroxy-α-amino acid derivatives with nitric acid, react with tributyltin hydride to give the corresponding alkoxyl radicals. These radicals readily undergo β-scission, providing a convenient route for the regiocontrolled production of α-carbon-centred amino acid radicals. By examining the partitioning of the alkoxyl radicals between the β-scission process and the competing hydrogen transfer reaction, it has been possible to evaluate the influence of electronic and steric effects on the β-scission reaction and the formation of the carbon-centred radicals.
- Easton, Christopher J.,Ivory, Andrew J.,Smith, Craig A.
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p. 503 - 507
(2007/10/03)
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- Preparation and Use of Aziridino Alcohols as Promoters for the Enantioselective Addition of Dialkylzinc Reagents to N-(Diphenylphosphinoyl) Imines
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A set of chiral aziridino alcohols 2-5 has been synthesized starting from either readily available amino acids (L-serine, L-threonine, and allo-L-threonine) or simple olefins (using Sharpless asymmetric aminohydroxylation and dihydroxylation reactions). Chiral ligands 2-5 have been tested as promoters for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl) imines 1. The influence of the substituants on the aziridine ring and the alcohol moiety on the selectivity has been studied, and in the best case, an enantiomeric excess of up to 94% could be obtained. Acidic hydrolysis of the initially formed N-protected amines 6 led to the corresponding free amines 7 without racemization. Although a stoichiometric amount of the ligand was used, about 90% of it could be recovered during the workup and reused without significant loss of chiral induction. The utility of the aziridino alcohols 2-5 as catalysts for the same reaction has also been evaluated and enantiomeric excesses of up to 76% were achieved using 0.25 equiv of the chiral ligand. A possible transition state for the addition reaction is also proposed.
- Andersson, Pher G.,Guijarro, David,Tanner, David
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p. 7364 - 7375
(2007/10/03)
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- Protein backbone modification by novel C(α)-C side-chain scission
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α-Ketoamide (-NH-CO-CO-) units in intact peptides are generated from Ser/Thr residues via Ru(VIII)-catalyzed C(α)-C side-chain scission. Facets associated with this novel α-carbon modification have been probed with 75 peptides chosen to represent every possible peptide environment. The reactions were carried out at room temperature with in situ generated Ru(VIII) in biphasic (CH3CN/CCl4/pH 3 phosphate buffer, 1:1:2 v/v) medium. Whereas Ser/Thr residues placed at the C-terminal end in peptides undergo N-C bond scission leading to des-Ser/Thr peptide amides - thus acting as Gly equivalents in simulating the α-amidating action of pituitary enzymes - those located at the N-terminal or nonterminal or even at the C-terminal position (protected as amide) were found to undergo oxidative C-C bond scission (involving C(α) and C side-chain bond), resulting in the generation of α-ketoamide (-NH-CO-CO-) units in the intact peptide backbone. The difference in the products arising from C(α)-C side-chain scission of Ser/Thr esters and amides is rationalized on the basis of a common mechanism involving either oxaloesters [PeP-NH-CO-COX; X = OMe] or oxalamides [X = NH2 or NH-Pep] arising from the oxidation of initially formed carbinolamide intermediates [Pep-NH-CH(OH)-COX], wherein, while the former are shown to undergo hydrolysis to terminal amides [Pep-NH2], the oxalamides are found to be stable to hydrolysis. Ancillary noteworthy findings are those of peptide bond scission when contiguous Ser-Ser/Thr-Thr residues are present and the oxidative cleavage at C-terminal Tyr/Trp sites generating des amides. The oxidative methodology presented here is mild, simple, and practical and proceeds with chiral retention. The insensitivity of a large number of amino acid residues, such as Gly, Ala, Leu, Asn, Gln, Asp, Glu, Pro, Arg, Phe, Lys, Val, and Aib, and N-protecting groups, such as Boc, Z, and Bz, toward Ru(VIII) under the experimental conditions should make this methodology practical and useful. Sulfur-containing amino acids Cys and Met get oxidized to sulfones in the products.
- Ranganathan,Vaish,Shah
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p. 6545 - 6557
(2007/10/02)
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- Resolution of β-hydroxy-α-amino acids by the action of proteases on their N-acyl methyl esters
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Methyl N-acetyl phenylserinates (1, 2), methyl N-acetyl nitrophenylserinates (3, 4), and methyl N-benzoyl threoninates (5, 6) were resolved conveniently into the enantiomers with high optical purities by enzymatic hydrolysis in the presence of α-chymotryp
- Chenevert, Robert,Letourneau, Martin,Thiboutot, Sonia
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p. 960 - 963
(2007/10/02)
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- Access to (S)-2-Methyloxetane and the Precursor (S)-1,3-Butanediol of Hight Enantiomeric Purity
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(S)-2-Methyloxetane (1) and its precursor (S)-1,3-butanediol (2) were prepared in low to moderate chemical yield with less than 0.5percent racemization from (S)-ethyl lactate (4) and from (2S,3S)-allothreonine (14b).For the first time the enantiomeric purities of both the starting material and the product (1) were carefully determined by high-precision capillary gas chromatography on optically active resolving stationary phases.The validity of the quadrant rule, correlating the relative configuration of alkyloxiranes with the order of elution from manganese(II) bis (3) by complexation gas chromatography, is also confirmed for 2-methyloxetane (1).
- Hintzer, Klaus,Koppenhoefer, Bernhard,Schurig, Volker
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p. 3850 - 3854
(2007/10/02)
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