- Hydrogenolysis of geminal diazides
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The complete hydrogenolysis of compounds containing the geminal diazido functionality is described. Using hydrogen over palladium on charcoal, the diazides are reduced, and primary amines are obtained. For example, aminomalonates and glycines are generated in a straightforward manner. A protocol that provides direct access to acetylated amines derived from 2-amino-1,3-diketones in good to excellent yields, via hydrogenation in the presence of acetic anhydride, is also presented.
- Biallas, Phillip,Kirsch, Stefan F.
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- Iridium porphyrin catalyzed N-H insertion reactions: Scope and mechanism
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Ir(TTP)CH3 catalyzed N-H insertion reactions between ethyl diazoacetate (EDA) or methyl phenyldiazoacetate (MPDA) and a variety of aryl, aliphatic, primary, and secondary amines to generate substituted glycine esters with modest to high yields. Aniline substrates generally gave yields above 80%, with up to 105 catalyst turnovers, and without slow addition of the diazo reagent. Good yields were also achieved with aliphatic amines, though higher catalyst loadings and slow addition of the amine were necessary in some cases. Primary amines reacted with EDA to generate both single- and double-insertion products, either of which could be produced selectively in high yield with the proper choice of stoichiometric ratios and reaction temperature. Notably, mixed trisubstituted amines, RN(CH2CO2Et) (CHPhCO2Me), were generated from the insertion of 1 equiv of EDA and 1 equiv of MPDA into primary amines. The N-H insertion mechanism was examined using substrate competition studies, trapping experiments, and multiple spectroscopic techniques. Substrate competition studies using pairs of amines with EDA or MPDA revealed Hammett correlations with respective slopes of ρ = 0.15 and ρ+ = -0.56 as well as kinetic isotope ratios of k H/kD = 1.0 ± 0.2 and 2.7 ± 0.2. Competitive amine binding to the iridium center was demonstrated by kinetics and equilibrium binding studies. Equilibrium binding constants ranged from 102 to 105. Monitoring the reaction by absorption spectroscopy revealed a transient metalloporphyrin complex. The lifetime of this species was dependent on the nature of the amine substrate, which suggests that the catalytic cycle proceeds through a metal-ylide intermediate.
- Anding, Bernie J.,Woo, L. Keith
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p. 2599 - 2607
(2013/06/26)
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- Chemoselectivity in coupling of azides with thioacids in solution-phase and solvent-free conditions
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Solvent-free rapid coupling of monothiocarboxylic acid with azide affords carboxamide chemoselectively. Triphenyl phosphine included as an additive influences the chemoselectivity, yielding carboxamide and thioamide. Similar variation in the chemoselectivity is observed in the absence and presence of triphenyl phosphine in solution-phase methodology. Rapidity and ecofriendliness of the solvent-free approach to yield the products in just 15min is noteworthy compared to the solution-phase protocol, which has a long reaction time (1-3 days).
- Nagarajan, Sangaraiah,Shanmugavelan, Poovan,Sathishkumar, Murugan,Priyadharshini, Namachivayam,Sudakar, Padmanaban,Ponnuswamy, Alagusundaram
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p. 668 - 680
(2013/01/15)
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- Copper-exchanged bentonite: A reusable catalysis for the formation of alkoxycarbonyl nitrile ylides under microwave irradiation
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Ethyldiazoacetate reacts as a carbene precursor in presence of copper exchanged bentonite. Reaction with excess nitrile gave oxazole derivatives. Their formation is explained by intramolecular 1,5-cyclisation of alkoxycarbonyl substituted nitrile ylide intermediate.
- Bendedouche, Choukri Kamel,Benhaoua, Hadj
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experimental part
p. 149 - 151
(2012/10/18)
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- Compounds
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Compounds of Formula (I), compositions containing them, their use in therapy, including their use as antibacterials, for example in the treatment of tuberculosis, and methods for the preparation of such compounds, are provided.
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Page/Page column 32
(2009/08/14)
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- Functionalizing glycine derivatives by direct C-C bond formation
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(Chemical Equation Presented) Come on glycine: Two different types of glycine derivatives are α-functionalized using cross-dehydrogenative- coupling (CDC) reactions. The method allows the efficient attachment of a malonate or aromatic alkyne group on the α-position of the glycine derivatives under very mild conditions.
- Zhao, Liang,Li, Chao-Jun
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supporting information; experimental part
p. 7075 - 7078
(2009/04/07)
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- ANTI-ODOR COMPOSITIONS AND THERAPEUTIC USE
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This application discloses a composition comprising a malodor compound and an anti-odor ingredient effective for reducing the presence or production of malodor. The composition may be topically applied to a subject and is useful for cosmetic conditions, pharmaceutical indications, or other objectives.
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- Competitive formation of 10- and 7-membered hydrogen-bonded rings of proline-containing model peptides
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Intramolecularly hydrogen-bonded structures of proline-containing model peptides with a sequence of N-tert-butoxycarbonyl-prolyl-Xaa-NHCH3 [Xaa = Gly (glycyl), Ala (alanyl), Phe (phenylalanyl), Leu (leucyl), Ile (isoleucyl), and Val (valyl)] were studied by proton nuclear magnetic resonance and infrared spectroscopy. Variation of chemical shifts of amide protons with composition change of DMSO-d6/CDCl3 mixed solvents were found to be a good measure of intramolecular hydrogen bonding of peptides in CDCl3 solution. It has been shown that 10- and 7-membered hydrogen-bonded rings, which should have the β- and γ-turn like structures in proteins, respectively, form competitively with each other. It is suggested that the equilibrium between the two hydrogen-bonded rings is determined by steric hindrance due to a side chain of the Xaa residue. Free energies for formation of the 10- and 7-membered hydrogen-bonded rings, ΔG10 and ΔG7, were estimated from the solvent composition-dependent change of the chemical shifts. A good correlation between ΔG10 and the occurrence frequencies of residues Xaa at the (i + 2)th position for the β-turns in proteins has been found.
- Jin, Yusuke,Tonan, Kenji,Ikawa, Shun-Ichi
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p. 2795 - 2802
(2007/10/03)
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- Reaction of 3-(Acetoxyamino)quinazolin-4(3H)-ones with Enolic β-Diketones: the N-N Bond as a Chiral Axis in N-(3,4-dihydro-4-oxoquinazolin-3-yl)-N-acyl-α-aminoketones; Reductive and Base-catalysed Cleavage of the N-N Bond in N-Acetyl-N-(3,4-dihydro-4-oxoquinazolin-3-yl)-α-amino Aci...
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Following the method of Foucaud and coworkers, reaction of pentane-2,4-dione with 3-(acetoxyamino)quinazolin-4-one 8 gave the keto amide 9 (15percent). 3-Methylpentane-2,4-dione reacts with compound 8 to give a relatively stable enol 11 (66percent) which can be isolated in a crystalline form.Rotation around the N-N bonds in both compounds 9 and 11 is believed to be slow on the real time-scale and hence the N-N bonds can be considered as a chiral axes.As a result, protonation of the enol double bond in compound 11 and the creation of an additional chiral centre, gives rise to the separable keto amides 14 and 15; this protonation can be accomplished completely diastereoselectively.Lead tetraacetate acetoxylation of compound 11 to give compound 11 to give compound 19 is also completely diastereoselective.Brief heating of the enol effects the elimination of the quinazolinone and the formation of the N-acetylimine 16 via an 8-membered transition state.Base-catalysed elimination of the quinazolinone ring from compound 22 is surprisingly easy: reductive cleavage of this N-N bond in compound 22 is facile by comparison with the 3-(alkylamino)quinazolin-4-ones.
- Atkinson, Robert S.,Edwards, Paul J.,Thomson, Gordon A.
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p. 3209 - 3216
(2007/10/02)
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- Synthesis of oxazoles and thiazoles using thioimidates
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Several oxazoles and thiazoles were synthesized easily by the reaction of N-(methylthioalkylidene)glycine ethyl ester with diethyl oxalate, acid halides, and thionesters in the presence of base.
- Yokoyama,Menjo,Watanabe,Togo
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p. 1467 - 1470
(2007/10/02)
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- Acylation de l'acetamidomalonate de diethyle. Synthese et reactivite du 4-ethoxycarbonyl oxazole
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The acylation of diethyl acetamidomalonate by palmitoyl chloride was performed using KOtBu in THF.Subsequent reaction of acylmalonate with DMSO or NMP led to ethyl 5-alkyloxazole-4-carboxylate (global yield 76percent for the two steps).Some original reactions of this heterocycle are presented, including ring opening of oxazole. - Keywords: amphiphilic compounds / Krapcho reaction / trans-acylation / oxazoles
- Loupy, Andre,Petit, Alain,Zaparucha, Anne,Mahieu, Claude,Semeria, Didier
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p. 642 - 647
(2007/10/02)
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- Asymmetric Induction Mediated by an N-N Chiral Axis
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Reaction of 3-methylpentane-2,4-dione 11 with N-acetoxyaminoquinazolinone 6 gives an isolable enol 12, which is chiral by virtue of the high barrier to rotation around its N-N bond; protonation of the double bond occurs in glacial acetic acid to give a single diastereoisomer of keto-amide 13.
- Atkinson, Robert S.,Edwards, Paul J.,Thomson, Gordon A.
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p. 1256 - 1257
(2007/10/02)
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- THE SYNTHESIS AND CHEMISTRY OF AZOLENINES. PART 20 ISOLATION OF 3H-PYRROLE-5-CARBOXYLATE ESTERS AND FRAGMENTATION PRODUCTS FROM THE REACTION BETWEEN 2,2-DISUBSTITUTED 1,3-DIKETONES AND GLYCINE ETHYL ESTER HYDROCHLORIDE
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The reaction between 3,3-dimethylpentane-2,4-dione (12a) and glycine ethyl ester hydrochloride (13) in the presence of sodium acetate and acetic acid gives moderate amounts each of ethyl 2,3,3,4-tetramethyl-3H-pyrrole-5-carboxylate (17a), a hydroxypyrroline precursor (15a) and a fragmentation product ethyl acetamidoacetate (14a).With the more sterically-crowded 2,2-dimethyl-1-phenylbutane-1,3-dione (12b), only very small amounts of two regioisomeric 3H-pyrroles (17b) and (18b) are found, fragmentation being the major reaction pathway: other 2,2-disubstituted 1,3-diketones studied gave only fragmentation products.A reaction scheme accounting for the various products is proposed.
- Lee, Sze-Ming,Sammes, Michael P.
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p. 2401 - 2410
(2007/10/02)
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- Synthesis and reactions of 3-alkoxy-2H-azirines
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3-Alkoxy-2H-azirines 4 have been prepared by treatment of enol ethers 6 with iodine azide followed by base-catalysed elimination of HI and thermolysis of the resulting vinyl azide 5.Azirines 4 readily undergo electrophilic additions, to yield products resulting from cleavage of either the N(1)-C(3) or the N(1)-C(2) bond.Reaction of 4 with trimethylsilyl cyanide yields highly functionalized aziridines 12.Thermolysis of 4 produces C-alkoxy-N-vinylmethanimines.
- Ghosez, L.,Sainte, F.,Rivera, M.,Bernard-Henriet, C.,Gouverneur, V.
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p. 456 - 461
(2007/10/02)
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- Interactions between Terminally Substituted Amino Acids in an Aqueous and a Non-Aqueous Environment. Enthalpic Interaction Coefficients in Water and in N,N-Dimethylformamide at 25 deg C
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Enthalpies of dilution of the N-acetyl amides of glycine, L-alanine, L-valine, L-leucine, and L-phenylalanine, dissolved in N,N-dimethylformamide (DMF) as a solvent have been measured at 25 deg C.The results obtained have been analyzed to give the enthalpic interaction (or virial) coefficients of the solutes and these are compared with information previously obtained in aqueous systems.There are marked differences in the interaction properties in the two solvents and, while the additivity approache of Savage and Wood is applicable to the solutes in water it is suitable for representing the interactions in DMF.A correlation is presented between the enthalpic second virial coefficients in DMF and the propensity of side-chains to be in proximity in globular proteins.
- Kent, Hilary E.,Lilley, Terence H.,Milburn, Peter J.,Bloemendal, Michael,Somsen, Gus
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p. 101 - 116
(2007/10/02)
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- Crown ether catalysis of decarboxylation and decarbalkoxylation of β-keto acids and malonates: a synthetic application
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The effect of 18-crown-6 ether on the decarboxylation rates of the sodium and potassium salts of 3-camphor carboxylic acid 1 and of 1-carbomethoxy-1-carboxycyclohexane 2 was studied.For 2 the K-18C6 salt reacted ca. 104 times faster than the parent acid.This remarkable difference in reactivity was used in developing a one-pot, two-step procedure for decarbalkoxylation of malonic esters.This procedure was then applied to a range of malonates, β-keto esters, and an α-cyano ester.The effect of 15C5, other cations, and good nucleophiles was also studied.
- Hunter, Duncan H.,Patel, Vijay,Perry, Richard A.
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p. 2271 - 2277
(2007/10/02)
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- Aminocarboxylic acid higher alkylamides
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Compounds of the formula EQU1 wherein R1 is lower alkyl or aryl, R2 is hydrogen or, together with R1, ethylene, and R3 is straight or branched alkyl of 8 to 22 carbon atoms; The compounds have useful therapeutic, dermatological and cosmetic properties.
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