- Direct Deamination of Primary Amines via Isodiazene Intermediates
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We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.
- Berger, Kathleen J.,Driscoll, Julia L.,Yuan, Mingbin,Dherange, Balu D.,Gutierrez, Osvaldo,Levin, Mark D.
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supporting information
p. 17366 - 17373
(2021/11/04)
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- Regiodivergent Enantioselective γ-Additions of Oxazolones to 2,3-Butadienoates Catalyzed by Phosphines: Synthesis of α,α-Disubstituted α-Amino Acids and N,O-Acetal Derivatives
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Phosphine-catalyzed regiodivergent enantioselective C-2- and C-4-selective γ-additions of oxazolones to 2,3-butadienoates have been developed. The C-4-selective γ-addition of oxazolones occurred in a highly enantioselective manner when 2-aryl-4-alkyloxazol-5-(4H)-ones were employed as pronucleophiles. With the employment of 2-alkyl-4-aryloxazol-5-(4H)-ones as the donor, C-2-selective γ-addition of oxazolones took place in a highly enantioselective manner. The C-4-selective adducts provided rapid access to optically enriched α,α-disubstituted α-amino acid derivatives, and the C-2-selective products led to facile synthesis of chiral N,O-acetals and γ-lactols. Theoretical studies via DFT calculations suggested that the origin of the observed regioselectivity was due to the distortion energy that resulted from the interaction between the nucleophilic oxazolide and the electrophilic phosphonium intermediate.
- Wang, Tianli,Yu, Zhaoyuan,Hoon, Ding Long,Phee, Claire Yan,Lan, Yu,Lu, Yixin
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supporting information
p. 265 - 271
(2016/01/25)
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- Synthesis and bioactivity of novel 3-(1-hydroxyethylidene)-5-substituted- pyrrolidine-2,4-dione derivatives
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Ten novel 5-substituted derivatives of 3-(1-hydroxyethylidene)pyrrolidine- 2,4-dione were synthesized. The compounds were confirmed by IR, 1H NMR, MS and elemental analysis. The bioassay indicated that these compounds showed noticeable herbicid
- Han, Bao Feng,Shi, Qing Ming,Wang, Xian Feng,Liu, Jian Bo,Qiang, Sheng,Yang, Chun Long
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experimental part
p. 1023 - 1026
(2012/10/08)
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- QUINAZOLINEDIONE CHYMASE INHIBITORS
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Disclosed are small molecule inhibitors which are useful in treating various diseases and conditions involving Chymase.
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Page/Page column 48
(2009/04/25)
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- Tandem multi-step synthesis of C-carboxyazlactones promoted by N-heterocyclic carbenes
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Cascade reaction sequences incorporating N-heterocyclic carbene-based organocatalysis have been developed that allow the direct preparation of a range of (±)-4-phenoxycarbonylazlactones in good isolated yields (66-84%) from the corresponding N-p-anisoyl amino acids. The Royal Society of Chemistry.
- Campbell, Craig D.,Duguet, Nicolas,Gallagher, Katherine A.,Thomson, Jennifer E.,Lindsay, Anita G.,O'Donoghue, AnnMarie C.,Smith, Andrew D.
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supporting information; body text
p. 3528 - 3530
(2009/02/05)
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- Resolution of non-protein amino acids via the microbial protease-catalyzed enantioselective hydrolysis of their N-unprotected esters
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In the Aspergillus oryzae protease-catalyzed ester hydrolysis, substitution of N-unprotected amino acid esters for the corresponding N-protected amino acid esters resulted in a large enhancement of the hydrolysis rate, while the enantioselectivity was deteriorated strikingly when the substrates employed were the conventional methyl esters. This difficulty was overcome by employing esters bearing a longer alkyl chain such as the isobutyl ester. Utilizing this ester, amino acids carrying an aromatic side chain were resolved with excellent enantioselectivities (E=50 to >200). With amino acids bearing an aliphatic side chain also, good results in terms of the hydrolysis rate and enantioselectivity were obtained by employing such an ester as the isobutyl ester. Moreover, the enantioselectivity proved to be enhanced further by conducting the reaction at low temperature. This procedure was applicable to the case where the enantioselectivity was not high enough even by the use of the isobutyl ester.
- Miyazawa, Toshifumi,Imagawa, Kiwamu,Minowa, Hiroe,Miyamoto, Toyoko,Yamada, Takashi
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p. 10254 - 10261
(2007/10/03)
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- New 2-(2'-phenyl-9'-benzyl-8'-azapurin-6'-ylamino)-carboxylic acid methylesters as ligands for A1 adenosine receptors.
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Synthesis of a series of new 2-phenyl-9-benzyl-8-azaadenines bearing on N6 an alkyl or aralkyl chain having a carbonyloxymethyl group on the carbon bound to N6 were reported. The ester group could assure to the molecule a better water-solubility than the 8-azaadenines 2, 6 and 9 substituted with lipophilic groups synthesised in the past. Compounds synthesised demonstrated only little capability of binding A1 adenosine receptors.
- Biagi,Giorgi,Pacchini,Livi,Scartoni
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p. 929 - 931
(2007/10/03)
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- Inhibitors of tripeptidyl peptidase II. 2. Generation of the first novel lead inhibitor of cholecystokinin-8-inactivating peptidase: A strategy for the design of peptidase inhibitors
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The cholecystokinin-8 (CCK-8)-inactivating peptidase is a serine peptidase which has been shown to be a membrane-bound isoform of tripeptidyl peptidase II (EC 3.4.14.10). It cleaves the neurotransmitter CCK-8 sulfate at the Met-Gly bond to give Asp-Tyr(SO3H)-Met-OH + Gly-Trp-Met-Asp-Phe-NH2. In seeking a reversible inhibitor of this peptidase, the enzymatic binding subsites were characterized using a fluorimetric assay based on the hydrolysis of the artificial substrate Ala-Ala-Phe-amidomethylcoumarin. A series of di- and tripeptides having various alkyl or aryl side chains was studied to determine the accessible volume for binding and to probe the potential for hydrophobic interactions. From this initial study the tripeptides Ile-Pro-Ile-OH (K(i) = 1 μM) and Ala-Pro-Ala-OH (K(i) = 3 μM) and dipeptide amide Val-Nvl-NHBu (K(i) = 3 μM) emerged as leads. Comparison of these structures led to the synthesis of Val-Pro-NHBu (K(i) = 0.57 μM) which served for later optimization in the design of butabindide, a potent reversible competitive and selective inhibitor of the CCK-8-inactivating peptidase. The strategy for this work is explicitly described since it illustrates a possible general approach for peptidase inhibitor design.
- Ganellin, C. Robin,Bishop, Paul B.,Bambal, Ramesh B.,Chan, Suzanne M. T.,Law, James K.,Marabout, Benoit,Luthra, Pratibha Mehta,Moore, Andrew N. J.,Peschard, Olivier,Bourgeat, Pierre,Rose, Christiane,Vargas, Froylan,Schwartz, Jean-Charles
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p. 664 - 674
(2007/10/03)
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- Oxidative deprotection of diphenylmethylamines
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(formula presented) The diphenylmethyl amino protecting group can be efficiently removed by initial oxidation of the amine to an imine by 2,3-dichloro-5,6-dicyanobenzoquinone. The resulting imine can then be easily hydrolyzed under mildly acidic conditions. This method is particularly well suited for the preparation of α-amino phosphinates and α-amino phosphonates.
- Sampson, Peter B.,Honek, John F.
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p. 1395 - 1397
(2008/02/09)
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- Non-Proteinogenic Amino Acid Synthesis: Synthesis of β,γ-Unsaturated α-Amino Acids from Aspartic Acid
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A general, stereospecific, synthesis of β,γ-unsaturated α-amino acids using the β-anion derived from aspartic acid is described.Keywords: aspartic acid; unsaturated acids
- Baldwin, Jack E.,Moloney, Mark G.,North, Michael
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p. 6319 - 6330
(2007/10/02)
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- RELATIONSHIPS BETWEEN THE STRUCTURE AND THE PHYTOTOXICITY OF THE FUNGAL TOXIN TENUAZONIC ACID
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Tenuazonic acid (3-acetyl 5-sec-butyl pyrrolidine-2,4-dione) is a metabolite produced by the fungal pathogen of rice Pyricularia oryzae.It inhibits growth of plants by interferring with protein synthesis at the ribosome level.We have synthesized analogues of tenuazonic acid with various substituents at C-3 and C-5.Substituents at C-5 other than sec-butyl or n-propyl, decrease the phytotoxicity of the analogues.But substitutions at C-3 abolish the toxicity.Thus, tenuazonic acid seems to have the optimal structure for phytotoxicity.Tenuazonic acid induces rice leaf defence reactions (browning) of reactive varieties which are resistant to P. oryzae.Some of the analogues synthesized have a low level of phytotoxicity and are able to induce this leaf browning of the reactive rice varieties.Thus different structural features are required for phytotoxicity and for leaf browning.Key Word Index - Tenuazonic acid; pyrrolidine-2,4-diones; rice; phytotoxicity; Pyricularia oryzae; structure-activity.
- Lebrun, M. H.,Nicolas, L.,Boutar, M.,Gaudemer, F.,Ranomenjanahary, S.,Gaudemer, A.
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