1069-48-3Relevant articles and documents
TRANSITION METAL COMPLEXES - A NEW CLASS OF CATALYSTS OF INTERFACIAL ALKYLATION FOR THE ASYMMETRICAL SYNTHESIS OF α-AMINO ACIDS
Belokon', Yu. N.,Maleev, V. I.,Videnskaya, S. O.,Saporovskaya, M. B.,Tsyryapkin, V. A.,Belikov, V. M.
, p. 110 - 118 (1991)
A new class of catalysts of interfacial asymmetrical alkylation is suggested for the synthesis of α-amino acids - positively charged complexes of the transition metals Cu(II), Ni(II), and Pd(II).These complexes consist of several fragments, by variation of which the structure of the catalysts can readily be modified.The complexes are chiral on account of (S)proline derivatives contained in them as one of the fragments.The catalyst complexes (C) were used in alkylation of amino acid fragments of Ni(II) complexes of the Schiff base of glycine with N-(2-pyridinecarbonyl)-o-aminobenzophenone (Ni-PBP-Gly) and the Schiff base of alanine with N-(2-pyridinecarbonyl)-o-aminobenzaldehyde (Ni-PBA-Ala) under interfacial conditions.After decomposition of alkylated complexes, phenylalanine and α-methyl-phenylalanine were isolated with yields of 33-87percent and optical purity (o. p.) from 3 to 21percent, depending on the C used.
Synthesis of chiral spiro 3-oxazolin-5-one 3-oxides (Chiral nitrones) via a nitrosoketene intermediate and their asymmetric 1,3-dipolar cycloaddition reactions leading to the EPC synthesis of modified amino acids,
Katagiri, Nobuya,Okada, Makoto,Morishita, Yoshihiro,Kaneko, Chikara
, p. 5725 - 5746 (1997)
Cycloaddition of chiral cyclic ketones such as (-)-menthone, (+)-nopinone, and (+)-camphenilone to nitrosokelene generated by thermolysis of 5-hydroxyimino-2,2-dimethyl-1,3-dioxane-4,6 dione gave the corresponding chiral spiro 3-oxazolin-5-one 3-oxides (chiral cyclic nitrones). These nitrones underwent asymmetric 1,3-dipolar cycloddition reactions with electron rich olefins to give the corresponding oxazolidine derivatives with high diastereoselectivity, which were converted to optically pure amino acids.
SYNTHESIS OF AMINO ACIDS. ALKYLATION OF ALDIMINE AND KETIMINE DERIVATIVES OF GLYCINE ETHYL ESTER UNDER VARIOUS PHASE-TRANSFER CONDITIONS
Ghosez, Leon,Antoine, Jean-Pierre,Deffense, Etienne,Navarro, Mirtha,Libert, Valery,et al.
, p. 4255 - 4258 (1982)
The Schiff base derived from glycine ethyl ester and p-chlorobenzaldehyde can be alkylated by the ion-pair extraction method as well as under catalytic liquid-liquid or solid-liquid phase-transfer conditions.This imine is compared with the corresponding benzophenone Schiff base.
Direct synthesis of unprotected α-amino acids via allylation of hydroxyglycine
Sugiura, Masaharu,Mori, Chieko,Hirano, Keiichi,Kobayashi, Shu
, p. 937 - 942 (2005)
Hydroxyglycine, the ammonia adduct of glyoxylic acid, was found to react with various allylboronates in the presence of triethylamine in methanol to give unprotected α-amino acids directly with high stereoselectivity. For instance, the reactions with (E)- and (Z)-crotylboronates afforded the corresponding anti- and syn-crotylated products (isoleucine and alloisoleucine after hydrogenation) with high diastereoselectivity, respectively. Interestingly, it was found that isomerization of the products (γ-adducts to α-adducts) occurred under the reaction conditions in some cases. Control experiments have suggested that the isomerization took place via 2-aza (or azonia) Cope rearrangement of imines derived from γ-adducts and glyoxylic acid.
Aqueous Ligand-Stabilized Palladium Nanoparticle Catalysts for Parahydrogen-Induced 13C Hyperpolarization
McCormick, Jeffrey,Grunfeld, Alexander M.,Ertas, Yavuz N.,Biswas, Akash N.,Marsh, Kristofer L.,Wagner, Shawn,Gl?ggler, Stefan,Bouchard, Louis-S.
, p. 7190 - 7194 (2017)
Parahydrogen-induced polarization (PHIP) is a method for enhancing NMR sensitivity. The pairwise addition of parahydrogen in aqueous media by heterogeneous catalysts can lead to applications in chemical and biological systems. Polarization enhancement can be transferred from 1H to 13C for longer lifetimes by using zero field cycling. In this work, water-dispersible N-acetylcysteine- and l-cysteine-stabilized palladium nanoparticles are introduced, and carbon polarizations up to 2 orders of magnitude higher than in previous aqueous heterogeneous PHIP systems are presented. P13C values of 1.2 and 0.2% are achieved for the formation of hydroxyethyl propionate from hydroxyethyl acrylate and ethyl acetate from vinyl acetate, respectively. Both nanoparticle systems are easily synthesized in open air, and TEM indicates an average size of 2.4 ± 0.6 nm for NAC@Pd and 2.5 ± 0.8 nm for LCys@Pd nanoparticles with 40 and 25% ligand coverage determined by thermogravimetric analysis, respectively. As a step toward biological relevance, results are presented for the unprotected amino acid allylglycine upon aqueous hydrogenation of propargylglycine.
One-Pot Synthesis of α-Amino Acids through Carboxylation of Ammonium Ylides with CO2 Followed by Alkyl Migration
Mita, Tsuyoshi,Sugawara, Masumi,Sato, Yoshihiro
, p. 5236 - 5243 (2016)
A simple, yet powerful protocol for α-amino acid synthesis using carbon dioxide (CO2) was developed. α-Amino silanes could undergo four successive reactions (formation of ammonium salt, carboxylation, esterification, and 2,3- or 1,2-Stevens rearrangement) in the presence of allylic or benzylic halides under a CO2 atmosphere (1 atm). It is noteworthy that carboxylation at the position adjacent to a nitrogen atom proceeded via an ammonium ylide intermediate under mild conditions.
Parahydrogen-Induced Polarization Relayed via Proton Exchange
Them, Kolja,Ellermann, Frowin,Pravdivtsev, Andrey N.,Salnikov, Oleg G.,Skovpin, Ivan V.,Koptyug, Igor V.,Herges, Rainer,H?vener, Jan-Bernd
supporting information, p. 13694 - 13700 (2021/09/07)
The hyperpolarization of nuclear spins is a game-changing technology that enables hitherto inaccessible applications for magnetic resonance in chemistry and biomedicine. Despite significant advances and discoveries in the past, however, the quest to establish efficient and effective hyperpolarization methods continues. Here, we describe a new method that combines the advantages of direct parahydrogenation, high polarization (P), fast reaction, and low cost with the broad applicability of polarization transfer via proton exchange. We identified the system propargyl alcohol + pH2 → allyl alcohol to yield 1H polarization in excess of P ≈ 13% by using only 50% enriched pH2 at a pressure of ≈1 bar. The polarization was then successfully relayed via proton exchange from allyl alcohol to various target molecules. The polarizations of water and alcohols (as target molecules) approached P ≈ 1% even at high molar concentrations of 100 mM. Lactate, glucose, and pyruvic acid were also polarized, but to a lesser extent. Several potential improvements of the methodology are discussed. Thus, the parahydrogen-induced hyperpolarization relayed via proton exchange (PHIP-X) is a promising approach to polarize numerous molecules which participate in proton exchange and support new applications for magnetic resonance.
Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
Maurs, Michele,Acher, Francine,Azerad, Robert
, p. 22 - 26 (2012/10/29)
In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
Microwave-assisted synthesis of unnatural amino acids
Young, Douglas D.,Torres-Kolbus, Jessica,Deiters, Alexander
experimental part, p. 5478 - 5480 (2009/05/30)
Microwave irradiation has been proven to be a useful tool in the rapid assembly of racemic unnatural amino acids in only two steps. Additional benefits of this methodology are the commercial availability of the inexpensive starting materials and the high yields and high purities of the final amino acid products.
α-aminoallylation of aldehydes with ammonia: Stereoselective synthesis of homoallylic primary amines
Sugiura, Masaharu,Hirano, Keiichi,Kobayashi, Shu
, p. 7182 - 7183 (2007/10/03)
Three-component reactions of aldehydes, ammonia, and allylboronates were found to provide homoallylic primary amines in high yields with high chemo- and stereoselectivities. A two-step, one-pot, stereoselective synthesis of an uncommon α-amino acid, alloisoleucine, was achieved utilizing this reaction. Copyright
