6456-74-2Relevant academic research and scientific papers
Preparation method of tert-butyl glycine
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, (2021/11/06)
The invention discloses a preparation method of tert-butyl glycine, and belongs to the technical field of organic synthesis. The raw materials are easily available, the process is simple, the process is simple, the reaction conditions are mild, the requirement for equipment is low, the total yield is up to 85 - 93%, and a significant amount of double-substituted by-products are effectively avoided in the direct reaction with ammonia in the traditional process.
A General Stereocontrolled Synthesis of Opines through Asymmetric Pd-Catalyzed N-Allylation of Amino Acid Esters
Albat, Dominik,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
supporting information, p. 2099 - 2102 (2021/07/22)
A stereo-divergent synthesis of natural and unnatural opines in stereochemically pure form is based on the direct palladium-catalyzed N-allylation of α-amino acid esters (up to 97 % ee or 99 : 1 d.r.) using methyl (E)-2-penten-4-yl carbonate in the presence of only 1 mol% of a catalyst, prepared in-situ from the C2-symmetric diphosphine iPr-MediPhos and [Pd(allyl)Cl]2. Selected target compounds (incl. a derivative of the drug enalapril) were efficiently obtained from the N-allylated intermediates by oxidative cleavage (ozonolysis) of the allylic C=C bond under temporary N-Boc-protection.
Single Electron Transfer-Induced Selective α-Oxygenation of Glycine Derivatives
Císa?ová, Ivana,Jahn, Ullrich,K?nig, Burkhard,Moser, Johannes,Venugopal, Navyasree,Vojtí?ková, Margaréta
supporting information, (2021/11/03)
Modification of amino acids is an important strategy in organic and bioorganic chemistry. In contrast to common side-chain functionalization, backbone modification is much less explored. Especially glycine units seem to be attractive and versatile since a wide range of functionality can be potentially introduced. We report here oxidative modification of glycinates that are stable and enable further functionalization. Selective glycinate enolate oxidation by TEMPO or a FeCp2PF6/TEMPO reagent combination provides stable alkoxyamines in good to excellent yields. The methodology is expanded to glycine-containing dipeptides demonstrating selective oxygenation at the glycine unit. The orthogonal reactivity potential of oxygenated glycines for transformation to other amino acid derivatives is explored.
Overcoming the Deallylation Problem: Palladium(II)-Catalyzed Chemo-, Regio-, and Stereoselective Allylic Oxidation of Aryl Allyl Ether, Amine, and Amino Acids
Begam, Hasina Mamataj,Jana, Ranjan,Manna, Kartic,Samanta, Krishanu
supporting information, p. 7443 - 7449 (2020/10/09)
We report herein a Pd(II)/bis-sulfoxide-catalyzed intramolecular allylic C-H acetoxylation of aryl allyl ether, amine, and amino acids with the retention of a labile allyl moiety. Mechanistically, the reaction proceeds through a distinct double-bond isomerization from the allylic to the vinylic position followed by intramolecular carboxypalladation and the β-hydride elimination pathway. For the first time, C-H oxidation of N-allyl-protected amino acids to furnish five-membered heterocycles through 1,3-syn-addition is established with excellent diastereoselectivity.
Multicomponent synthesis of pyroglutamic acid derivatives: Via Knoevenagel-Michael-hydrolysis-lactamization-decarboxylation (KMHL-D) sequence
Khopade, Tushar M.,Warghude, Prakash K.,Sonawane, Amol D.,Bhat, Ramakrishna G.
supporting information, p. 561 - 566 (2019/01/24)
A novel and practical method for the synthesis of 3-substituted pyroglutamic acid derivatives is described. One pot multicomponent reaction of Meldrum's acid, aldehyde and Schiff's base followed an unprecedented chemoselective Knoevenagel-Michael-hydrolysis-lactamization domino sequence to afford 4-carboxy 3-substituted pyroglutamic acid derivatives under mild conditions. A carboxy intermediate formed appears to accelerate its own formation. The generality of the synthesis is exemplified by the use of a wide variety of aldehydes including enolizable aliphatic aldehydes, while substrates are stable under reaction conditions.
Simple and efficient Fmoc removal in ionic liquid
Di Gioia,Costanzo,De Nino,Maiuolo,Nardi,Olivito,Procopio
, p. 36482 - 36491 (2017/08/02)
A mild method for an efficient removal of the fluorenylmethoxycarbonyl (Fmoc) group in ionic liquid was developed. The combination of a weak base such as triethylamine and [Bmim][BF4] makes the entire system more efficient for the cleavage at room temperature of various amines and amino acid methyl esters in short reaction times. The procedure works well even in the case of N-Fmoc amino acids bearing acid-sensitive protecting groups and of N-alkylated amino acid methyl esters. The solvent-free condition provides a complementary method for Fmoc deprotection in solution phase peptide synthesis and modern organic synthesis.
Efficient Synthesis of 11C-Acrylesters, 11C-Acrylamides and Their Application in Michael Addition Reactions for PET Tracer Development
Filp, Ulrike,Pees, Anna L.,Taddei, Carlotta,Peko?ak, Aleksandra,Gee, Antony D.,Windhorst, Albert D.,Poot, Alex J.
supporting information, p. 5154 - 5162 (2017/09/20)
Here we present a new Michael addition reaction utilizing carbon-11 labeled acrylic esters and amides. Subsequently, reactions of these synthons with commercially available Schiff base precursors are performed to produce [11C]glutamate and [11C]glutamine. This methodology is especially useful for the development of positron emission tomography (PET) imaging agents as it offers a new array of potential carbon-11 labeled compounds with this original 11C–C bond forming strategy.
Total synthesis of (-)-platensimycin by advancing oxocarbenium- and iminium-mediated catalytic methods
Eey, Stanley T.-C.,Lear, Martin J.
, p. 11556 - 11573 (2015/01/16)
(-)-Platensimycin is a potent inhibitor of fatty acid synthase that holds promise in the treatment of metabolic disorders (e.g., diabetes and "fatty liver") and pathogenic infections (e.g., those caused by drug-resistant bacteria). Herein, we describe its total synthesis through a four-step preparation of the aromatic amine fragment and an improved stereocontrolled assembly of the ketolide fragment, (-)-platensic acid. Key synthetic advances include 1) a modified Lieben haloform reaction to directly convert an aryl methyl ketone into its methyl ester within 30 seconds, 2) an experimentally improved dialkylation protocol to form platensic acid, 3) a sterically controlled chemo- and diastereoselective organocatalytic conjugate reduction of a spiro-cyclized cyclohexadienone by using the trifluoroacetic acid salt of α-amino di-tert-butyl malonate, 4) a tetrabutylammonium fluoride promoted spiro-alkylative para dearomatization of a free phenol to assemble the cagelike ketolide core with the moderate leaving-group ability of an early tosylate intermediate, and 5) a bismuth(III)-catalyzed Friedel-Crafts cyclization of a free lactol, with LiClO4 as an additive to liberate a more active oxocarbenium perchlorate species and suppress the Lewis basicity of the sulfonyloxy group. The longest linear sequence is 21 steps with an overall yield of 3.8% from commercially available eugenol. Relay tactics: The stereocontrolled assembly of the potent antibiotic (-)-platensimycin in 21 steps and 3.8% yield from eugenol is described (see scheme; TBAF: tetrabutylammonium fluoride; Ts: toluene-4-sulfonyl). Highlights are 1) a rapid oxidative esterification of an acyl aromatic, 2) a reliable dialkylation protocol to form platensic acid, 3) a π-facial conjugate reduction of a dienone, 4) a TBAF-promoted alkylative dearomatization of a free phenol, and 5) a Friedel-Crafts closure of a free lactol.
Chiral iminoesters derived from d-glyceraldehyde in [3+2] cycloaddition reactions. Asymmetric synthesis of a key intermediate in the synthesis of neuramidinase inhibitors
Galvez, Jose A.,Diaz-De-Villegas, Maria D.,Alias, Miriam,Badorrey, Ramon
, p. 11404 - 11413 (2013/12/04)
Silver-catalyzed endo-selective and copper-catalyzed exo-selective asymmetric [3 + 2] cycloadditions of acrylates to chiral iminoesters derived from d-glyceraldehyde have been investigated. The reaction diastereoselectively provides highly functionalized pyrrolidines. This approach was used to develop the first asymmetric synthesis of a key intermediate in the synthesis of pyrrolidine influenza neuramidinase inhibitors.
Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: Tailored gold-based anticancer peptidomimetics
Negom Kouodom, Morelle,Ronconi, Luca,Celegato, Marta,Nardon, Chiara,Marchiò, Luciano,Dou, Q. Ping,Aldinucci, Donatella,Formaggio, Fernando,Fregona, Dolores
scheme or table, p. 2212 - 2226 (2012/05/05)
Complexes [AuIIIX2(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [AuIIIBr2(dtc-Sar-Aib-O(t- Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC50 values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.
