- O-to-S Substitution Enables Dovetailing Conflicting Cyclizability, Polymerizability, and Recyclability: Dithiolactone vs. Dilactone
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Developing chemically recyclable polymers represents a greener alternative to landfill and incineration and offers a closed-loop strategy toward a circular materials economy. However, the synthesis of chemically recyclable polymers is still plagued with certain fundamental limitations, including trade-offs between the monomer's cyclizability and polymerizability, as well as between polymer's depolymerizability and properties. Here we describe the subtle O-to-S substitution, dithiolactone monomers derived from abundant feedstock α-amino acids can demonstrate appealing chemical properties different from those of dilactone, including accelerated ring closure, augmented kinetics polymerizability, high depolymerizability and selectivity, and thus constitute a unique class of polythioester materials exhibiting controlled molecular weight (up to 100.5 kDa), atactic yet high crystallinity, structurally diversity, and chemical recyclability. These polythioesters well addresses the formidable challenges of developing chemically recyclable polymers by having an unusual set of desired properties, including easy-to-make monomer from ubiquitous feedstock, and high polymerizability, crystallinity and precise tunability of physicochemical performance, as well as high depolymerizability and selectivity. Computational studies explain why O-to-S modification of polymer backbone enables dovetailing desirable, but conflicting, performance into one polymer structure.
- Chen, Jinlong,Li, Maosheng,Tao, Youhua,Wang, Xianhong,Wang, Yanchao
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supporting information
p. 22547 - 22553
(2021/09/09)
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- A novel lipase from Aspergillus oryzae catalyzed resolution of (R,S)-ethyl 2-bromoisovalerate
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In this study, a novel lipase M5 derived from Aspergillus oryzae WZ007 was prone to exhibit high hydrolytic activity and stereoselectivity towards racemic substrate (R,S)-ethyl 2-bromoisovalerate. (R)-ethyl 2-bromoisovalerate was obtained by enzymatic resolution, which is the key chiral intermediate for highly efficient enantiomerically fluvalinate. The results showed that the enzymatic reaction was carried out in 120mM racemic substrate for 3 hours, the enantiomeric excess reached 98.6%, the conversion was 51.7%, and E value above 120. Therefore, the novel lipase M5 has the ability to efficiently produce (R)-ethyl 2-bromoisovalerate, which greatly reduces the industrial production cost of the highly efficient counterpart of fluvalinate.
- Wu, Peng,Zhang, Mengjie,Zhang, Yinjun,Wang, Zhao,Zheng, Jianyong
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p. 231 - 238
(2019/12/27)
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- Ribosomal Synthesis of Backbone-Cyclic Peptides Compatible with in Vitro Display
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Backbone-cyclic peptides are an attractive class for therapeutic development. However, in vitro display technologies coupled with ribosomal synthesis are intrinsically inapplicable to such "phenotypes" because of loss of the C-terminal peptide region linking to "genotype". Here, we report a methodology enabling the display of backbone-cyclic peptides. To achieve this, genetic code reprogramming was utilized to implement a rearrangement strategy involving the ribosomal incorporation of a designer initiator containing a thiazolidine-protected cysteine and 2-chloroacetoamide (ClAc) side chain, followed by an α-thio acid and cysteine at downstream positions. Upon expression of the linear peptide, spontaneous thioester rearrangement occurs between the α-thioester and the thiol group of the cysteine, liberating the α-thio group and resulting in cross-linking to the upstream ClAc side-chain group. Then selective deprotection of the thiazolidine-protected cysteine immediately promotes intramolecular native chemical ligation, as demonstrated for various sequences and ring sizes. In this approach, the backbone-cyclic peptides retain their C-terminal peptide regions via the side-chain thioether covalent linkage, making them compatible with in vitro display.
- Takatsuji, Ryo,Shinbara, Koki,Katoh, Takayuki,Goto, Yuki,Passioura, Toby,Yajima, Ryo,Komatsu, Yamato,Suga, Hiroaki
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supporting information
(2019/02/14)
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- Benzo six-membered nitrogen heterocyclic compound, preparation method and applications
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The present invention provides a benzo six-membered nitrogen heterocyclic compound, a preparation method and applications, wherein the benzo six-membered nitrogen heterocyclic compound has a structurerepresented by a formula I or formula II, and can effectively inhibit the bromine domain receptor and effectively inhibit the proliferation of cancer cells. Compared with the existing reported structure types, the compound of the present invention has different binding mode, has high inhibitory activity, can be used as a drug for treating cancer, cell proliferation disorders, inflammatory diseases, autoimmune diseases, septicemia and viral infections, and has good application prospects and high application value.
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Paragraph 0174-0175
(2019/10/01)
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- Benzoxazinone-containing 3,5-dimethylisoxazole derivatives as BET bromodomain inhibitors for treatment of castration-resistant prostate cancer
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The bromodomain and extra-terminal proteins (BET) have emerged as promising therapeutic targets for the treatment of castration-resistant prostate cancer (CRPC). We report the design, synthesis and evaluation of a new series of benzoxazinone-containing 3,5-dimethylisoxazole derivatives as selective BET inhibitors. One of the new compounds, (R)-12 (Y02234), binds to BRD4(1) with a Kd value of 110 nM and blocks bromodomain and acetyl lysine interactions with an IC50 value of 100 nM. It also exhibits selectivity for BET over non-BET bromodomain proteins and demonstrates reasonable anti-proliferation and colony formation inhibition effect in prostate cancer cell lines such as 22Rv1 and C4-2B. The BRD4 inhibitor (R)-12 also significantly suppresses the expression of ERG, Myc and AR target gene PSA at the mRNA level in prostate cancer cells. Treatment with (R)-12 significantly suppresses the tumor growth of prostate cancer (TGI = 70%) in a 22Rv1-derived xenograft model. These data suggest that compound (R)-12 is a promising lead compound for the development of a new class of therapeutics for the treatment of CRPC.
- Xue, Xiaoqian,Zhang, Yan,Wang, Chao,Zhang, Maofeng,Xiang, Qiuping,Wang, Junjian,Wang, Anhui,Li, Chenchang,Zhang, Cheng,Zou, Lingjiao,Wang, Rui,Wu, Shuang,Lu, Yongzhi,Chen, Hongwu,Ding, Ke,Li, Guohui,Xu, Yong
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supporting information
p. 542 - 559
(2018/05/24)
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- Cobalt-Catalyzed Cross-Coupling of α-Bromo Amides with Grignard Reagents
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A cobalt-catalyzed cross-coupling between α-bromo amides and Grignard reagents is disclosed. The reaction is general and allows access to a large variety of α-aryl and β,γ-unsaturated amides. Some mechanistic investigations have been undertaken to determine the nature of the intermediate species.
- Barde,Guérinot,Cossy
-
supporting information
p. 6068 - 6071
(2017/11/28)
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- Solid phase synthesis of 1,3,4-oxadiazin-5 (6R)-one and 1,3,4-oxadiazol-2-one scaffolds from acyl hydrazides
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Solid phase synthesis of 1,3,4-oxadiazin-5(6R)-one and 1,3,4-oxadiazol-2-one scaffolds from resin-bound acyl hydrazides is described. We demonstrate here that the reactions of resin-bound aryl or hetero-aromatic acyl hydrazides with 2-substituted-2-bromoacetic acids and 4-nitrophenyl chloroformate and subsequent treatment with DIEA lead to intramolecular cyclization reactions to produce six-membered 1,3,4-oxadiazin-5(6R)-ones and five-membered 1,3,4-oxadiazol-2-ones, respectively. We also show that acyl hydrazide-derived 1,3,4-oxadiazol-2-ones may be useful serine hydrolase inhibitors. This journal is
- Sarma, Bani Kanta,Liu, Xiaodan,Wu, Hao,Gao, Yu,Kodadek, Thomas
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supporting information
p. 59 - 63
(2015/02/02)
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- Synthesis of enantiomerically enriched-bromonitriles from amino acids
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Two methods were investigated for the preparation of six chiral-bromonitriles with different optic purities. The nitrous deamination of amino acids gives-bromoacids, which react with chlorosulfonyl isocyanate followed by triethylamine to afford-bromonitriles with moderate enantiomeric excess. However, the dehydration of corresponding-bromoamids using thionyl chloride gives-bromonitriles with good enantiomeric excess up to 94%. The use of phosphoryl chloride instead of thionyl chloride results in more than 30% racemization as determined by high-performance liquid chromatograpic analysis.
- Tka, Najeh,Kraem, Jamil,Hassine, Bechir Ben
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p. 735 - 743
(2013/01/15)
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- Discovery of a potent, orally active 11β-hydroxysteroid dehydrogenase type 1 inhibitor for clinical study: Identification of (S)-2-((1 S,2 S,4 R)-Bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5 H)-one (AMG 221)
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Thiazolones with an exo-norbornylamine at the 2-position and an isopropyl group on the 5-position are potent 11β-HSD1 inhibitors. However, the C-5 center was prone to epimerization in vitro and in vivo, forming a less potent diastereomer. A methyl group was added to the C-5 position to eliminate epimerization, leading to the discovery of (S)-2-((1S,2S,4R)-bicyclo[2.2.1] heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221). This compound decreased fed blood glucose and insulin levels and reduced body weight in diet-induced obesity mice.
- Véniant, Murielle M.,Hale, Clarence,Hungate, Randall W.,Gahm, Kyung,Emery, Maurice G.,Jona, Janan,Joseph, Smriti,Adams, Jeffrey,Hague, Andrew,Moniz, George,Zhang, Jiandong,Bartberger, Michael D.,Li, Vivian,Syed, Rashid,Jordan, Steven,Komorowski, Renée,Chen, Michelle M.,Cupples, Rod,Kim, Ki Won,St. Jean, David J.,Johansson, Lars,Henriksson, Martin A.,Williams, Meredith,Vallg?rda, Jerk,Fotsch, Christopher,Wang, Minghan
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supporting information; scheme or table
p. 4481 - 4487
(2010/09/04)
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- Synthesis of α-bromoisovaleric acid in the poliphosphoric acid medium
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Bromination of isovaleric acid with bromine in the polyphosphoric acid mediumis was studied, regularities of the process including influence of the polyphosphoric acid composition were revealed, the process was shown technologically attractive for the organization of industrial manufacturing of α-bromoisovaleric acid.
- Malin,Malin,Laskin
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p. 511 - 512
(2008/09/20)
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- Investigation of the synthetic and mechanistic aspects of the highly stereoselective transformation of α-thioamides to α-thio-β- chloroacrylamides
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Treatment of a series of α-thioamides with N-chlorosuccinimide results in efficient transformation to the analogous α-thio-β- chloroacrylamides. The mechanistic pathway has been established through isolation and characterisation of intermediate compounds. The scope of the transformation has been explored - aryl and alkylthio substituents, primary, secondary and tertiary amides can be employed. In most instances, the chloroacrylamides are formed exclusively as the Z-stereoisomer; however, with tertiary propanamides or with amides derived from butanoic or pentanoic acid a mixture of E- and Z-stereoisomers is formed. The Royal Society of Chemistry.
- Murphy, Maureen,Lynch, Denis,Schaeffer, Marcel,Kissane, Marie,Chopra, Jay,O'Brien, Elisabeth,Ford, Alan,Ferguson, George,Maguire, Anita R.
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p. 1228 - 1241
(2008/02/03)
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- A novel series of parenteral cephalosporins exhibiting potent activities against Pseudomonas aeruginosa and other Gram-negative pathogens: Synthesis and structure-activity relationships
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A series of 7β-[2-(2-aminothiazol-4-yl)-2-(Z)-(carboxymethoxyimino)acetamido]cephalosporins bearing a 1-(substituted)-1H-pyrrolo[3,2-b]pyridinium group at C-3′ position was synthesized and their in vitro antibacterial activities against Pseudomonas aeruginosa and other Gram-negative pathogens were evaluated. Among the cephalosporins prepared, 7β-[2-(2-amino-5-chlorothiazol-4yl)-2(Z)-((S)-1-carboxyethoxyimino)acetamido]cephalosporins (42d) showed potent antibacterial activities against P. aeruginosa and other Gram-negative pathogens including the strains which produce class C β-lactamase and extended spectrum β-lactamase (ESBL). These results imply that both the Cl atom on the C-7 aminothiazole moiety and the α-substituent at the iminoether moiety are essential for the stability against β-lactamase and the potent activity against Gram-negative bacteria including P. aeruginosa.
- Yamawaki, Kenji,Nomura, Takashi,Yasukata, Tatsuro,Uotani, Koichi,Miwa, Hideaki,Takeda, Kei,Nishitani, Yasuhiro
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p. 6716 - 6732
(2008/03/28)
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- Synthesis and structures of (S)- and (R)-2-[3-cyano-4-(2-thienyl)-5,6,7, 8-tetrahydroquinolin-2-ylsulfanyl]-3-methyl-N-phenylbutyramide
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(S)- and (R)-2-[3-cyano-4-(2-thienyl)-5,6,7,8-tetrahydroquinolin-2- ylsulfanyl]-N-phenyl-3-methylbutyramide (1a and 1b) were prepared from 2-thiophenaldehyde and D- and L-valines, respectively, and their crystal structures were elucidated by X-ray crystallography.
- Yao, Zhiyi,Du, Xiaojie,Liu, Hong,Jiang, Hualiang,Chen, Kaixian
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- PROCESS FOR PRODUCTION OF OPTICALLY ACTIVE 2-HALOGENO- CARBOXYLIC ACIDS
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The invention provides processes for producing efficiently optically active 2-halogenocarboxylic acids useful in the preparation of drugs or the like and salts thereof with amines. Specifically, an optically active 2-halogenocarboxylic acid is produced by halogenating an optically active amino acid in water in the presence of a hydrophobic organic solvent and nitrous acid with the configuration retained and with the racemization inhibited through the removal of 2-hydroxy- bromocarboxylic acid formed as a by-product; the obtained optically active 2-halogenocarboxylic acid is transferred to an aqueous phase by converting it into a salt thereof with a base, followed by the removal of the organic phase; and the optically active 2-halogenocarboxylic acid is transferred again to an organic solvent phase, followed by the removal of the aqueous phase, whereby an optically active 2-halogenocarboxylic acid is obtained through the removal of a halogen component. Further, a high-quality salt of an optically active 2-halogenocarboxylic acid with an amine can be obtained by a crystallization method wherein the amine is added over the period of 1/2 hour or longer either continuously or in portions and/or wherein the crystallization solvent consists of a hydrophobic organic solvent and a hydrophilic organic solvent.
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- Mercaptoacetylamide derivatives, a process for their preparation and their use
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This invention discloses and claims a series of mercaptoacetylamide derivatives of formula I. Also disclosed and claimed are pharmaceutical compositions incorporating these compounds and processes for preparing said compounds. The use of said compounds for inhibition of the enzymes angiotensin converting enzyme and neutral endopeptidase, and for the treatment of hypertension and congestive heart failure are also disclosed and claimed.
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- Synthesis and biological activity of novel potent endothelin-converting enzyme-1 inhibitors
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Through directed screening of metalloprotease inhibitors, CGS 30084 (1) has been identified as a potent endothelin-converting enzyme-1 (ECE-1) inhibitor in vitro (IC50 = 77 nM). Herein we report the syntheses and biological activities of analogues derived from this lead, based on modifications of the biphenyl moiety. Compound 10, the thioacetate methyl ester prodrug derivative of compound 6m, was found to be an orally active and potent inhibitor of ECE-1 activity in rats.
- Firooznia, Fariborz,Gude, Candido,Chan, Kenneth,Fink, Cynthia A.,Qiao, Ying,Satoh, Yoshitaka,Marcopoulos, Nicholas,Savage, Paula,Beil, Michael E.,Bruseo, Charles W.,Trapani, Angelo J.,Jeng, Arco Y.
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p. 375 - 378
(2007/10/03)
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- N-hdroxy-2-(alkyl, aryl, or heteroaryl, sulfanyl, sulfinyl or sulfonyl)-3-substituted alkyl, aryl or heteroarylamides as matrix metalloproteinase inhibitors
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Matrix metalloproteinases (MMPs) are a group of enzymes that have been implicated in the pathological destruction of connective tissue and basement membranes. These zinc containing endopeptidases consist of several subsets of enzymes including collagenases, stromelysins and gelatinases. TNF-α converting enzyme (TACE), a pro-inflammatory cytokine, catalyzes the formation of TNF-α from membrane bound TNF-α precursor protein. It is expected that small molecule inhibitors of MMPs and TACE therefore have the potential for treating a variety of disease states. The present invention provides low molecular weight, non-peptide inhibitors of matrix metalloproteinases (MMPs) and TNF-α converting enzyme (TACE) for the treatment of arthritis, tumor metastasis, tissue ulceration, abnormal wound healing, periodontal disease, bone disease, diabetes (insulin resistance) and HIV infection having the formula wherein R2and R3form a heterocyclic ring and A is S, S(O), or S(O)2, and R1and R4are defined herein.
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- Enantioselective synthesis of α-bromo acid derivatives and bromohydrins from tartrate derived bromoacetals
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Bromination of the acetals 4 derived from aryl alkyl ketones, ArCOR, and (2R,3R)-tartaric acid results in bromoacetals 5 with 78-90% de. Hydrolysis of those compounds with Ar = 4-methoxyphenyl or 3-bromo-4-methoxyphenyl results, after recrystallisation, in α-bromoketones 8 with 66-98% ee which are shown to undergo the Baeyer-Villiger oxidation to α-bromoesters 9 with minimal racemisation, α-Bromoketone 8d is shown to undergo carbonyl reduction to threo-bromohydrin 15 with retention of stereochemistry.
- Boyes, Scott A.,Hewson, Alan T.
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p. 2759 - 2765
(2007/10/03)
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- Efficient large scale preparation of neutral endopeptidase/ angiotensin-converting enzyme dual inhibitor CGS30440
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The development and piloting of a potential manufacturing process for ACE/NEP dual inhibitor CGS30440 is described. The synthesis proceeds sequentially from 1-aminocyclopentanecarboxylic acid via N-protection, peptide coupling with L-tyrosine ethyl ester, O-methylation of N-protected [(1-amino-1-cyclopentyl)carbonyl]-L-tyrosine ethyl ester, N-deprotection, peptide coupling of [(1-amino-1-cyclopentyl)carbonyl]-O-methyl-L-tyrosine ethyl ester with D-2-bromo-3-methylbutyric acid, and final displacement of bromide with thioacetate. This approach is superior to shorter Discovery routes based upon final peptide coupling of L-2-(acetylthio)-3-methylbutanoic acid to [(1-amino-1-cyclopentyl)carbonyl]-O-methyl-L-tyrosine ethyl ester.
- Johnson, Erik P.,Cantrell Jr., William R.,Jenson, Todd M.,Miller, Scott A.,Parker, David J.,Reel, Noela M.,Sylvester, Leo G.,Szendroi, Robert J.,Vargas, Kevin J.,Xu, Jean,Carlson, John A.
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p. 238 - 244
(2013/09/08)
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- Mercaptoacyl matrix metalloproteinase inhibitors: The effect of substitution at the mercaptoacyl moiety
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The in vitro potency of orally-active mercaptoacyl matrix metalloproteinase inhibitors is increased by the introduction of appropriate substitutents on the mercaptoacyl moiety.
- Baxter, Andrew D.,Bhogal, Ranjev,Bird, John B.,Buckley, George M.,Gregory, David S.,Hedger, Paul C.,Manallack, David T.,Massil, Tracy,Minton, Kevin J.,Montana, John G.,Neidle, Stephen,Owen, David A.,Watson, Robert J.
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p. 2765 - 2770
(2007/10/03)
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- N-[MERCAPTOACYL(AMINO ACID OR PEPTIDE)] COMPOUNDS AND S-LIPOPHILIC ALIPHATIC CARBONYL DERIVATIVES THEREOF AS ANTIHYPERTENSIVES
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N-[Mercaptoacyl(amino acid or peptide)] compounds and S-lipophilic aliphatic carbonyl derivatives thereof, and pharmaceutical compositions comprising such compounds, as well as the use of these compounds as antihypertensives by the inhibition of neutral endopeptidase and/or peptidyldipeptidase A are disclosed. Methods for preparing the such compounds and derivatives are disclosed also.
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- (R)- and (S)-3-Hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone as chiral auxiliaries for the asymmetric synthesis of α-hydroxy acids
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Rac-α-bromo acids, rac-4, have been converted into(R)- or(S)-α-hydroxy acids, (R)- or (S)-9 by DCC-induced esterification with the chiral auxiliaries (R)or (S)-1, followed by reaction with sodium p-methoxyphenoxide in the presence of tetra-n-hexylammonium iodide, conditions of dynamic kinetic resolution, to give quite diastereoselectively the (αR,3S)- or (αS,3R)-α-(p-methoxyphenoxy) esters, 7, which were then oxidized with eerie ammonium nitrate and hydrolyzed under controlled acid conditions.
- Camps, Pelayo,Perez, Francesc,Soldevilla, Nuria
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p. 1877 - 1894
(2007/10/03)
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- Optimal recognition of neutral endopeptidase and angiotensin-converting enzyme active sites by mercaptoacyldipeptides as a means to design potent dual inhibitors
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An interesting approach for the treatment of congestive heart failure and chronic hypertension could be to avoid the formation of angiotensin II by inhibiting angiotensin converting enzyme (ACE) and to protect atrial natriuretic factor by blocking neutral endopeptidase 24.11 (NEP). This is supported by recent results obtained with potent dual inhibitors of the two zinc metallopeptidases, such as RB 105, HSCH2CH(CH3)PhCONHCH(CH3)COOH (Fournie-Zaluski et al. Proc. Natl. Acad. Sci. U.S.A. 1994, 91, 4072-4076), which reduces blood pressure in experimental models of hypertension, independently of the salt and renin angiotensin system status. In order to develop new dual inhibitors with improved affinities, long duration of action, and/or better bioavailabilities, various series of mercaptoacyldipeptides corresponding to the general formula HSCH(R1)CONHCH(R1')CON(R)CH(R2')COOH have been synthesized. The introduction of well-selected β-branched chains in positions R1 and R1', associated with a tyrosine or a cyclic amino acid in the C-terminal position, led to potent dual inhibitors of NEP and ACE such as 21 [N-[(2S)-2-mercapto- 3-methylbutanoyl]-Ile-Tyr] and 22 [N-[(2S)-2-mercapte-3-phenylpropanoyl]Ala- Pro] which have IC50 values in the nanomolar range for NEP and subnanomolar range for ACE. These compounds could have different modes of binding to the two peptidases. In NEP, the dual inhibitors seem to interact only with the S1' and S2' subsites, whereas additional interactions with the S1 binding subsite of ACE probably account for their subnanomolar inhibitory potencies for this enzyme. The localization of the Pro residue of 22 outside the NEP active site is supported by biochemical data using (Arg102,Glu)NEP and molecular modeling studies with thermolysin used as model of NEP. One hour after oral administration in mice of a single dose (2.7 x 10-5 mol/kg), 21 inhibited 80% and 36% of kidney NEP and lung ACE, respectively, while 22 inhibited 40% of kidney NEP and 56% of lung ACE.
- Coric, Pascale,Turcaud, Serge,Meudal, Hervé,Roques, Bernard Pierre,Fournie-Zaluski, Marie-Claude
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p. 1210 - 1219
(2007/10/03)
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- Asymmetric Synthesis of 2-Chloro- and 2-Bromo-alkanoic acids by Halogenation of α-D-Glucofuranose-Derived Silyl Ketene Acetals.
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Optically active (S)-2-bromo- and 2-chloro-alkanoic acids 6 and 7 have been obtained via the diastereoselective halogenation of chiral silyl ketene acetals 3a-f, and subsequent saponification of the resulting crude esters.Examples characterized by e.e. values up to 95percent are reported.The diastereoface selectivity is independent of the silyl ketene acetal E/Z configuration.
- Angibaud, P.,Chaumette, J. L.,Desmurs, J. R.,Duhamel, L.,Ple, G.,et al.
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p. 1919 - 1932
(2007/10/03)
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- Acylmercaptoalkanoyldipeptides, methods of preparation and their therapeutic use
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This invention is directed to a compound of the formula that inhibits simultaneously neutral endopeptidase and peptidyldipeptidase A and is useful in treating hypertension. The invention is also directed to the preparation of the compound, pharmaceutical compositions containing it, and methods for its pharmaceutical use.
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- Nucleophilic Substitution Reactions of Alkyl Halides By Using New Polymer-Supported Reagents Containing Hemin
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A new polymer reagent consisting of hemin, divinylbenzene, and 2-methyl-5-vinylpyridine was synthesized by suspension copolymerization.Substitution reactions of primary, secondary, and tertiary alkyl halides with the hemin copolymer combined with cyanide, azide, and thiocyanate ions were given satisfactory yields.This reaction mechanism was revealed to be a SNi type on the basis of stereochemical study.The hemin copolymer was not only a polymer-supported reagent with functional capabilities, but also served to separate the product from the reaction mixture.
- Saito, Kiyoshi,Harada, Kaoru
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p. 2562 - 2566
(2007/10/02)
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- The Determination of Small Amounts of Enantiomeric Impurities in α-Halo Carboxylic Acids
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The accurate determination of the enantiomeric composition of α-halo carboxylic acids is reported.Such data are of importance in the synthesis of chiral compounds and in mechanistic studies involving the title compounds.
- Watabe, K.,Chang, S.-C.,Gil-Av, E.,Koppenhoefer, B.
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p. 225 - 228
(2007/10/02)
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- Preparation of α-Bromo- and α-Chlorocarboxylic Acids from α-Amino Acids
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Diazotization of α-amino acids in 48:52 (w/w) hydrogen fluoride/pyridine along with excess of potassium halide results in the corresponding α-halocarboxylic acids in good to excellent yields (Table 1 and 2).
- Olah, George A.,Shih, Joseph,Prakash, G. K. Surya
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p. 1028 - 1030
(2007/10/02)
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- Pesticidal esters of amino acids
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Novel diastereomeric esters of amino acids, novel intermediates therefor, synthesis thereof, and the use of said esters for the control of pests.
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