1190-76-7Relevant academic research and scientific papers
Direct catalytic asymmetric addition of allyl cyanide to ketones via soft lewis acid/hard bronsted base/hard lewis base catalysis
Yazaki, Ryo,Kumagai, Naoya,Shibasaki, Masakatsu
supporting information; experimental part, p. 5522 - 5531 (2010/07/04)
We report that a hard Lewis base substantially affects the reaction efficiency of direct catalytic asymmetric γ-addition of allyl cyanide (1a) to ketones promoted by a soft Lewis acid/hard Bronsted base catalyst. Mechanistic studies have revealed that Cu/(R,R)-Ph-BPE and Li(OC 6H4-p-OMe) serve as a soft Lewis acid and a hard Bronsted base, respectively, allowing for deprotonative activation of 1a as the rate-determining step. A ternary catalytic system comprising a soft Lewis acid/hard Bronsted base and an additional hard Lewis base, in which the basicity of the hard Bronsted base Li(OC6H4-p-OMe) was enhanced by phosphine oxide (the hard Lewis base) through a hard-hard interaction, outperformed the previously developed binary soft Lewis acid/hard Bronsted base catalytic system, leading to higher yields and enantioselectivities while using one-tenth the catalyst loading and one-fifth the amount of 1a. This second-generation catalyst allows efficient access to highly enantioenriched tertiary alcohols under nearly ideal atom-economical conditions (0.5-1 mol % catalyst loading and a substrate molar ratio of 1:2).
Synthesis of aryliminoacetonitriles under FVT conditions or by dehydrogenation of arylaminoacetonitriles: an NMR and UV-photoelectron spectroscopy study
Le?niak, Stanis?aw,Chrostowska, Anna,Kuc, Dawid,Maciejczyk, Ma?gorzata,Khayar, Sa?d,Nazarski, Ryszard B.,Urbaniak, ?ukasz
experimental part, p. 10581 - 10589 (2010/02/28)
The synthesis of [(E)-arylimino]-acetonitriles 3 has been described. It was found that the title compounds can be obtained on the three ways, namely by: (i) dehydrogenation of arylaminoacetonitriles 1, (ii) thermal fragmentation of 1-aryl-4-cyano-β-lactams 4 and (iii) retro-ene reaction of (allyl-p-methoxyphenyl-amino)-acetonitrile (7a) under FVT conditions. 1H and 13C NMR spectra of compounds 3, 5 and 6, and all their precursors 1 and 4, were recorded and analysed in detail using chemical shifts δH and δC [from GIAO DFT B3LYP/6-31(d) calculations] and J-couplings predicted at the DFT B3LYP/IGLO-II level. Also, UV-photoelectron spectra of 4a,d and 3a,d were measured and analysed considering the theoretical evaluation of their ionisation potentials.
The thermal decomposition of 5-membered rings: A laser pyrolysis study
Hore, Nathan R.,Russell, Douglas K.
, p. 606 - 613 (2007/10/03)
The mechanisms of pyrolysis of cyclopentadiene, furan, pyrrole and thiophene have been investigated using a combination of IR laser powered homogeneous pyrolysis, chemical and physical trapping of radical intermediates, and use of precursors specifically designed to generate selected radical intermediates. The results confirm the central role played by free radicals in the cases of cyclopentadiene and thiophene, and the dominant step of 1,2-H shifts in the cases of furan and pyrrole. The experimental results may be interpreted according to the high level ab initio calculations recently reported in the literature.
Synthesis and spectroscopic characterization of 1-13C- and 4-13C-plastoquinone-9
Boers, Rutger B.,Randulfe, Yolanda Pazos,Van Der Haas, Hendrikus N. S.,Van Rossum-Baan, Marleen,Lugtenburg, Johan
, p. 2094 - 2108 (2007/10/03)
This paper presents the synthesis of 1-13C- and 4-13C-plastoquinone-9 and their characterization with NMR spectroscopy and mass spectrometry. The synthetic scheme has been further adapted to introduce 13C-labeled plastoquinones on all individual and on each combination of positions in the quinone ring. Also a two-step scheme is disclosed to prepare unlabeled plastoquinone-9. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
(E)-Selective hydrolysis of (E,Z)-α,β-unsaturated nitriles by the recombinant nitrilase AtNIT1 from Arabidopsis thaliana
Effenberger, Franz,Osswald, Steffen
, p. 2581 - 2587 (2007/10/03)
From stereoisomeric α,β-unsaturated nitriles (E,Z)-1, the recombinant nitrilase AtNIT1 from Arabidopsis thaliana hydrolyses the (E)-isomers exclusively to the corresponding (E)-carboxylic acids (E)-2 with high specificity. The (E)-selectivity can also be utilised for the preparation of the isomerically pure nitriles (Z)-1. From (E,Z)-2-hydroxycinnamonitrile (E,Z)-3, the otherwise difficult obtainable (Z)-3 was prepared in 66% isolated yield. With β,γ-unsaturated (E,Z)-3-heptenenitrile (E,Z)-4, however, (E)-selectivity was not observed. AtNIT1 exhibits not only diastereoselectivity but also regioselectivity. From a mixture of the four isomers A-D of 3-(2-cyanocyclohex-3-enyl)propenenitrile 6, exclusively isomer D ((E)-cis-6) was hydrolysed to 3-(2-cyanocyclohex-3-enyl)propenoic acid (E)-cis-7, as stated by X-ray crystal structure. Only after complete conversion of D and high enzyme concentrations, isomer C ((E)-trans-6) was hydrolysed to a small extent.
Deamination Reactions, 54. - Decomposition of 1-Cyano-1-propanediazonium Ions
Bunse, Michael,Kirmse, Wolfgang
, p. 1499 - 1502 (2007/10/02)
The nitrous acid decomposition of 2-aminobutanenitrile (9) was studied with regard to product distribution and stereochemistry.The formation of 2-(hydroxyimino)butanenitriles (21, 22; 8-28percent) indicates the intervention of 1-cyanopropyl radicals (24) that are captured by NO.The polar reactions lead mainly to elimination (10-13) and nucleophilic substitution (14-16), rearrangement playing a minor role. (R)-9 was prepared from (R)-2-aminobutanoic acid.The nitrous acid deamination of (R)-9 afforded the cyanohydrin 16 with 81percent net inversion.Owing to destabilization of the carbocation 26 by CN, the SN2 route of nucleophilic displacement is preferred over SN1.The influence of CN is shown to be smaller than that of CF3. Key Words: α-Cyanodiazonium ions / α-Cyanoalkyl radicals / Carbocations, destabilized / Substitution, nucleophilic / Deamination reactions / Diazonium ions / Radicals
Solid Base-catalysed Rearrangement of Methacrylonitrile to Crotononitrile
Kurokawa, Hideki,Nakamura, Satoru,Ueda, Wataru,Morikawa, Yutaka,Moro-oka, Yoshihiko,Ikawa, Tuneo
, p. 658 - 659 (2007/10/02)
MgO and CaO catalysts have shown high activity for the formation of crotonitrile (cis/trans=6/4) in the rearrangement of methacrylonitrile.
Wittig Reactions of Ylide Anions derived from Stabilised Ylides
McKenna, Eugene G.,Walker, Brian J.
, p. 568 - 569 (2007/10/02)
Ester- and nitrile-stabilised ylide anions are more reactive than the corresponding ylides and react with aldehydes and ketones to give alkenes in good yields; the reactivity of stabilised triphenylphosphonium ylides is greatly increased by the replacement of one phenyl substituent.
Chemie der α-Aminonitrile. 1. Mitteilung. Einleitung und Wege zu Uroporphyrinogen-octanitrilen
Ksander, Gary,Bold, Guido,Lattmann, Rene,Lehmann, Christian,Frueh, Thomas,et al.
, p. 1115 - 1172 (2007/10/02)
Chemistry of α-Aminonitriles I: Introduction and Pathways to Uroporphyrinogen-octanitriles.An introduction to experimental studies on the chemistry of α-aminonitriles potentially relevant to the problems of prebiotic chemistry is presented.The framework of conditions wherein the investigations is chosen to be carried out implies both molecular oxygen and - whenever feasible - water to be excluded from reaction conditions.This study focusses on 2-amino-2-propenenitrile (3) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5).Schemes 13, 16, 23 as well as 25, and 26 summarize reaction sequences by which 3 is tranformed within the definied framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroporphyrinogen-octanitriles 57-60.HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one present in all biological porphinoids.Preparative procedures for the synthesis of 3 (Scheme 9), the β,β-disubstututed pyrrol-nitriles 30, 53, and 54 (Scheme 19) as well as the porphyrinogen-octakis(propionitrile) and -octakis(acetonitrile) 65 and 66, respectively (Scheme 24) are given.
Infrared Multiphoton Isomerization Reactions of Alkenes and Dienes
Lewis, Frederick D.,Teng, Peter,Weitz, Eric
, p. 2818 - 2826 (2007/10/02)
The infrared multiphoton laser-induced unimolecular isomerization reactions of several simple alkenes, conjugated alkenes, and pentadienes have been investigated.Excitation of (E)-2-butene, pentene, and hexene results in contrathermodynamic E -> Z isomerization and fragmentation, the isomerization/fragmentation ratio decreasing with increasing chain length and increasing laser fluence.These results are in qualitative agreement with RRKM calculations for average reactant energies of 75-85 kcal/mol.In addition to products of C-C homolysis observed with all three alkenes, 1-butene and 1,3-butadiene are formed from (E)-2-butene. (E)-Crotononitrile undergoes laser-induced isomerization without fragmentation, resulting in quantitative conversion to the Z isomer.In contrast, (E)-methyl crotonate undergoes both isomerization and fragmentation, while (E)-ethyl crotonate undergoes essentially quantitative elimination of ethylene.Irradiation of (E)- or (Z)-1,3-pentadiene at low laser fluences results exclusively in E Z isomerization resulting in steady-state isomer ratios which depend upon the relative magnitude of the single photon cross sections of the two isomers.At higher fluences, both isomers are converted to cyclopentadiene and trace amounts of 1,4-pentadiene.Irradiation of 1,4-pentadiene results in efficient isomerization to (E)- and (Z)-1,3-pentadiene which reacts further to yield cyclopentadiene.The factors which govern these and related infrared multiphoton reactions are discussed.
