- Titanium-Catalyzed Cyano-Borrowing Reaction for the Direct Amination of Cyanohydrins with Ammonia
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α-Aminonitrile was an important building block in natural products and key intermedia in organic chemistry. Herein, the direct amination of cyanohydrins with the partner of ammonia to synthesis N-unprotected α-aminonitriles is developed. The reaction proceeds via titanium-catalyzed cyano-borrowing reaction, which features high atom economy and simple operation. A broad range of ketone or aldehyde cyanohydrins was tolerated with ammonia, and the N-unprotected α-aminonitriles were synthesis with moderate to high yields under mild reaction conditions.
- Li, Qing-Hua,Li, Zhao-Feng,Tao, Jing,Li, Wan-Fang,Ren, Li-Qing,Li, Qian,Peng, Yun-Gui,Liu, Tang-Lin
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supporting information
p. 8429 - 8433
(2019/10/14)
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- Prebiotic selection and assembly of proteinogenic amino acids and natural nucleotides from complex mixtures
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A central problem for the prebiotic synthesis of biological amino acids and nucleotides is to avoid the concomitant synthesis of undesired or irrelevant by-products. Additionally, multistep pathways require mechanisms that enable the sequential addition of reactants and purification of intermediates that are consistent with reasonable geochemical scenarios. Here, we show that 2-aminothiazole reacts selectively with two- and three-carbon sugars (glycolaldehyde and glyceraldehyde, respectively), which results in their accumulation and purification as stable crystalline aminals. This permits ribonucleotide synthesis, even from complex sugar mixtures. Remarkably, aminal formation also overcomes the thermodynamically favoured isomerization of glyceraldehyde into dihydroxyacetone because only the aminal of glyceraldehyde separates from the equilibrating mixture. Finally, we show that aminal formation provides a novel pathway to amino acids that avoids the synthesis of the non-proteinogenic α,α-disubstituted analogues. The common physicochemical mechanism that controls the proteinogenic amino acid and ribonucleotide assembly from prebiotic mixtures suggests that these essential classes of metabolite had a unified chemical origin.
- Islam, Saidul,Bu?ar, Dejan-Kre?imir,Powner, Matthew W.
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p. 584 - 589
(2017/05/31)
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- Approaches to the construction of substituted 4-amino-1 H -pyrrol-2(5 H)-ones
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Fully substituted 4-aminopyrrolones are easily accessed via simple routes starting from imines, ketones, or α-bromophenyl acetonitriles. Imines were reacted with KCN/NH4Cl in aqueous ethanol to produce α-arylamino benzyl cyanides. On the other hand, ketones were transformed to the desired α-amino nitriles using a modified Strecker reaction. Then, α-amino nitrile precursors were allowed to react with a suitable acyl halide to produce the corresponding amides. Further treatment of these amides with ethanolic KOH converted them to highly substituted 4-amino-1H-pyrrol-2(5H)- one derivatives in moderate to excellent yields.
- Zali-Boeini, Hassan,Mobin, Mehdi,Hajibabaei, Khadijeh,Ghani, Maryam
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experimental part
p. 5808 - 5812
(2012/07/31)
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- Synthesis and conformational analysis of efrapeptins
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The efrapeptin family of peptide antibiotics produced by the fungus Tolypocladium niveum, and the neo-efrapeptins from the fungus Geotrichum candidumare inhibitors of F1-ATPase with promising antitumor, antimalaria, and insecticidal activity. They are rich in Cα- dialkyl amino acids (Aib, Iva, Acc) and contain one β-alanine and several pipecolic acid residues. The C-terminus bears an unusual heterocyclic cationic cap. The efrapeptins C-G and three analogues of efrapeptin C were synthesized using α-azido carboxylic acids as masked amino acid derivatives. All compounds display inhibitory activity toward F1-ATPase. The conformation in solution of the peptides was investigated with electronic CD spectroscopy, FT-IR spectroscopy, and VCD spectroscopy. All efrapeptins and most efrapeptin analogues were shown to adopt helical conformations in solution. In the case of efrapeptin C, VCD spectra proved that a 310-helix prevails. In addition, efrapeptin C was conformationally studied in detail with NMR and molecular modeling. Besides NOE distance restraints, residual dipolar couplings (RDC) observed upon partial alignment with stretched PDMS gels were used for the conformational analysis and confirmed the 310-helical conformation. Copyright
- Weigelt, Sven,Huber, Thomas,Hofmann, Frank,Jost, Micha,Ritzefeld, Markus,Luy, Burkhard,Freudenberger, Christoph,Majer, Zsuzsanna,Vass, Elemer,Greie, Joerg-Christian,Panella, Lavinia,Kaptein, Bernard,Broxterman, Quirinus B.,Kessler, Horst,Altendorf, Karlheinz,Hollosi, Miklos,Sewald, Norbert
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supporting information; experimental part
p. 478 - 487
(2012/03/08)
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- An automatic solid-phase synthesis of peptaibols
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An automated approach to peptaibols using microwave-assisted solid-phase peptide synthesis is demonstrated with a combination of HBTU and acid fluoride mediated couplings for normal and α,α-dialkylated amino acids, respectively. The method is utilized for
- Hjorringgaard, Claudia U.,Pedersen, Jan M.,Vosegaard, Thomas,Nielsen, Niels Chr,Skrydstrup, Troels
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supporting information; experimental part
p. 1329 - 1332
(2009/08/08)
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- Studies on phosphoroheterocycle chemistry II: A simple and new route to 1,3,2-diazaphospholidine-4-thione 2-sulfide derivatives
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A simple and new method for the synthesis of phosphoroheterocycles 1,3,2-diazaphospholidine-4-thione 2-sulfide derivatives by treatment of Lawesson's reagent (LR) with a variety of α-aminonitriles has been developed. The same methodology was also used in the preparation of fused phosphoroheterocycle 6 from 5-amino-4-cyano-3-methylthia-l-phenylpyrazole. The possible mechanism of the reaction involving addition of P-SH to the nitrile and subsequent rearrangement is proposed.
- Deng,Liu
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p. 2445 - 2449
(2007/10/03)
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- Process for the preparation of 4-oxoimidazolinium salts
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4-Oxoimidazolinium salts of the general formula: STR1 wherein R1 and R2 independently of one another are C1-10 -alkyl, C2-10 -alkenyl, C3-7 -cycloalkyl or optionally substituted aryl, arylalkyl, heteroaryl or heteroarylalkyl, or R1 and R2, together with the carbon atom to which they are bonded, form a three-membered to seven-membered saturated or unsaturated carbocyclic or heterocyclic ring, R3 is a C1-10 -alkyl group, C1-10 -alkenyl group, C3-7 -cycloalkyl group, aryl group, arylalkyl group or heteroaryl group, and A-- is an anion of a strong acid, are prepared by the cyclization of an α-acylaminonitrile in a nonaqueous solvent, in the presence of a lower alcohol and a strong acid. The compounds are intermediates for pharmaceutical active substances, for example, angiotensin II antagonists.
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- Liquid azonitrile mixtures
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Liquid mixtures of symmetrical and asymmetrical azonitriles are provided which have a maximum freezing point of 25° C. including mixtures of: A. 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylhexanonitrile) and 2-[(1-cyano-1-methylpropyl)azo]-2-methylhexanonitrile; B. 2,2-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylheptanonitrile) and 2-[(1-cyano-1-methylpropyl)azo]-2-methyl-heptanonitrile; C. 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-ethylhexanonitrile) and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylhexanonitrile; D. 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-ethylheptanonitrile) and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylheptanonitrile; E. 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methyloctanonitrile) and 2-[(1-cyano-1-methylpropyl)azo]-2-methyloctanonitrile; F. 2,2'-azobis(2-methylpentanonitrile), 2,2'-azobis(2-ethylhexanonitrile) and 2-[(1-cyano-1-methylbutyl)azo]-2-ethylhexanonitrile; G. 2,2'-azobis(2-methylhexanonitrile), 2,2'-azobis(2-methyloctanonitrile) and 2-[(1-cyano-1-methylpentyl)azo]-2-methyloctanonitrile; H. 2,2'-azobis(2-methylpentanonitrile), 2,2'-azobis(2-ethylheptanonitrile) and 2-[(1-cyano-1-methylbutyl)azo]-2-ethylheptanonitrile; I. 2,2'-azobis(2-methylhexanonitrile, 2,2'-azobis(2-methylheptanonitrile) and 2-[(1-cyano-1-methylpentyl)azo]-2-methylheptanonitrile; J. 2,2'-azobis(2-methylpentanonitrile), 2,2'-azobis(2-methyloctanonitrile) and 2-[(1-cyano-1-methylbutyl)azo]-2-methyloctanonitrile; K. 2,2'-azobis(2-methylpentanonitrile), 2,2'-azobis(2-methylhexanonitrile) and 2-[(1-cyano-1-methylbutyl)azo]-2-methylhexanonitrile; L. 2,2'-azobis(2-methylpentanonitrile), 2,2'-azobis(2-methylheptanonitrile) and 2-[(1-cyano-1-methylbutyl)azo]-2-methylheptanonitrile; and M. 2,2'-azobis(2-methylhexanonitrile), 2,2'-azobis(2-ethylheptanonitrile) and 2-[(1-cyano-1-methylpentyl)azo]-2-ethylheptanonitrile. The above liquid mixtures are useful as polymerization initiators in high pressure polymerization reactions.
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