- A new strategy for designing non-C2-symmetric monometallic bifunctional catalysts and their application in enantioselective cyanation of aldehydes
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A monometallic bifunctional catalyst, in which only one imidazolyl moiety is directly attached at the 3-position of a binaphthol moiety, has been developed. The ligand (R)-1, which lacks C2-symmetry and flexible linkers, in combination with Ti(OiPr)4, has been demonstrated to promote the enantioselective cyanation of aldehydes with trimethylsilylcyanide (TMSCN), giving excellent enantioselectivities of up to 98 % ee and high yields of up to 99%. The use of this bifunctional catalytic system obviates the need for additives and is extremely simple as the reagents are added in one portion at the beginning of the reaction. The protocol has been found to tolerate a relatively wide range of aldehydes when 10 mol% of the (R)-1/Ti(OiPr) 4 complex is deployed in CH2Cl2 at -40°C, the conditions which proved most practical and effective. The asymmetric cyanations also proceeded with lower catalyst loadings (5 mol%, or even 2 mol%), still giving satisfactory enantiomeric excesses and yields. Interestingly, the use of freshly distilled TMSCN dried over CaH2 gave a low enantioselectivity and only a moderate yield of the adduct as compared with direct use of the commercial reagent. The results of 13C NMR spectroscopic studies implicate HCN as the actual reactive nucleophile.
- Yang, Fei,Wei, Siping,Chen, Chien-An,Xi, Peihua,Yang, Li,Lan, Jingbo,Gau, Han-Mou,You, Jingsong
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- Copper-Catalyzed Substitution of α-Triflyloxy Nitriles and Esters with Silicon Nucleophiles under Inversion of the Configuration
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A copper-catalyzed nucleophilic displacement of α-triflyloxy nitriles and esters with silicon nucleophiles allows for the stereospecific generation of highly enantioenriched α-silylated carboxyl compounds. The enantioselective synthesis of α-silylated nitriles is unprecedented. The catalytic system exhibits good functional group tolerance. The stereochemical course of the substitution is shown to proceed with inversion of the configuration. The new reaction is an addition to the still limited number of methods for catalytic C(sp3)-Si cross-coupling.
- Scharfbier, Jonas,Hazrati, Hamideh,Irran, Elisabeth,Oestreich, Martin
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- Asymmetric trimethylsilylcyanation of aldehydes utilizing chiral bismuth compounds. A frontier in bismuth mediated synthetic reactions
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Bismuth(III) chloride (BiCl3) was found to work efficiently as a versatile catalyst for cyanation of aldehydes with trimethylsilyl cyanide to afford the corresponding cyanohydrins in high yields. Triphenylbismuthan (Ph3Bi) is also effective. The reaction has been applied to the asymmetric cyanation of a variety of aldehydes in high yields with moderate to good enantioselectivities by use of a chiral bismuth catalyst prepared in situ from BiCl3 and (2R,3R)-(+)-diethyl tartrate.
- Wada, Makoto,Takahashi, Toshikazu,Domae, Terutomo,Fukuma, Tomohiro,Miyoshi, Norikazu,Smith, Keith
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- Enzyme catalysed formation of (S)-cyanohydrins derived from aldehydes and ketones in a biphasic solvent system
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By employing a vigorously stirred two phase system aqueous buffer/organic solvent and using the hydroxynitrile lyase from Hevea brasiliensis as biocatalyst enantiopure (S)-cyanohydrins from aliphatic, unsaturated, aromatic and heteroaromatic aldehydes and methyl alkyl and methyl phenyl ketones are obtained in high yield and in general 98-99% enantiomeric excess.
- Griengl, Herfried,Klempier, Norbert,Poechlauer, Peter,Schmidt, Michael,Shi, Nongyuan,Zabelinskaja-Mackova, Antonina A.
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- Enantioselective trimethylsilylcyanation of aldehydes
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A chiral titanium reagent derived from optically active sulfoximine (R)-3 and Ti(O-i-Pr)4 promotes the asymmetric addition of trimethylsilylcyanide to aldehydes affording cyanohydrins in high yields with good enantioselectivities (up to 91% ee).
- Bolm, Carsten,Mueller, Peter
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- Catalysis of aldehyde and imine silylcyanation by platinum and palladium NCN-pincer complexes
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The room temperature addition of trimethylsilylcyanide to aromatic and aliphatic aldehydes to give the corresponding cyanohydrins is efficiently catalysed by 1 mol% of ((2,6-bis(N-cyclohexyl)imino)phenyl)aquoplatinum(II) trifluoromethanesulfonate 1a. This methodology is also applicable to the addition of trimethylsilylcyanide to Schiff bases resulting in the formation of α-amino nitriles.
- Fossey, John S.,Richards, Christopher J.
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- Cyanosilylation of aldehydes catalyzed by N-heterocyclic carbenes
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N-Heterocyclic carbenes produced in situ from salts of imidazolium, benzimidazolium, pyrido[1,2-c]imidazolium, imidazolinium, thiazolium, and triazolium catalyze the addition of trimethylsilylcyanide to aldehydes to yield cyanohydrin trimethylsilyl ethers. The use of C2-symmetric imidazolidenyl carbene derived from (R,R)-1,3-bis[(1-naphthyl)ethyl]imidazolium chloride led to enantioselective cyanosilylation.
- Suzuki, Yumiko,Bakar, M.D., Abu,Muramatsu, Kazuyuki,Sato, Masayuki
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- Mechanism-Based inactivation of human cytochrome p450 3A4 by two piperazine-Containing compounds
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Human cytochrome P450 3A4 (CYP3A4) is responsible for the metabolism of more than half of pharmaceutic drugs, and inactivation of CYP3A4 can lead to adverse drug-drug interactions. The substituted imidazole compounds 5-fluoro-2-[4-[(2-phenyl-1H-imidazol-5-yl) methyl]-1-piperazinyl]pyrimidine (SCH 66712) and 1-[(2-ethyl-4-methyl-1H-imidazol-5-yl)methyl]-4-[4-(trifluoromethyl)-2-pyridinyl]piperazine (EMTPP) have been previously identified as mechanism-based inactivators (MBI) of CYP2D6. The present study shows that both SCH 66712 and EMTPP are also MBIs of CYP3A4. Inhibition of CYP3A4 by SCH 66712 and EMTPP was determined to be con-centration, time, and NADPH dependent. In addition, inactivation of CYP3A4 by SCH 66712 was shown to be unaffected by the presence of electrophile scavengers. SCH 66712 displays type I binding to CYP3A4 with a spectral binding constant (Ks) of 42.9 ± 2.9 μM. The partition ratios for SCH 66712 and EMTPP were 11 and 94, respectively. Whole protein mass spectrum analysis revealed 1:1 binding stoichiometry of SCH 66712 and EMTPP to CYP3A4 and a mass increase consistent with adduction by the inactivators without addition of oxygen. Heme adduction was not apparent. Multiple monooxygenation products with each inactivator were observed; no other products were apparent. These are the first MBIs to be shown to be potent inactivators of both CYP2D6 and CYP3A4.
- Bolles, Amanda K.,Fujiwara, Rina,Briggs, Erran D.,Nomeir, Amin A.,Furge, Laura Lowe
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- Enantioselective synthesis of aliphatic cyanohydrin acetates
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When the standard conditions for the enantioselective synthesis of cyanohydrin acetates via dynamic kinetic resolution are applied to aliphatic substrates, only a kinetic resolution is observed. However, by exchanging the base (Amberlite) against NaCN, qu
- Veum, Lars,Hanefeld, Ulf
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- Development of β-hydroxyamide/titanium complexes for catalytic enantioselective silylcyanation of aldehydes
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A highly enantioselective addition of trimethylsilylcyanide to aldehydes catalyzed by chiral titanium complexes is described. The chiral titanium complexes were prepared in situ from Ti(OiPr)4 and β-hydroxyamide ligands, that could easily be synthesized from ketopinic acid and C2 symmetrical chiral diamines in a small number of steps. Graphical Abstract.
- Uang, Biing-Jiun,Fu, I-Pin,Hwang, Chyuan-Der,Chang, Chun-Wei,Yang, Chun-Tzu,Hwang, Der-Ren
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- The Asymmetric Hydrocyanation of Aldehydes with Cyanotrimethylsilane Promoted by a Chiral Titanium Reagent
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The asymmetric hydrocyanation of aldehydes with cyanotrimethylsilane proceeds by the use of a chiral alkoxy titanium(IV) to give the corresponding cyanohydrins with good enantioselectivity.
- Narasaka, Koichi,Yamada, Tohru,Minamikawa, Hiroyuki
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- Application of crude preparations of leaves from food plants for the formation of cyanohydrins with high enantiomeric excesses
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Crude preparations obtained from mamey (Pouteria sapota), capulin (Prunus serotina var. capulli) and peach (Prunus persica) leaves were used to catalyze the enantioselective addition of HCN to a variety of aldehydes. The corresponding cyanohydrins were obtained with high levels of enantioselectivity, comparable with those obtained with other catalysts used for the same purpose.
- Hernandez, Liliana,Luna, Hector,Solis, Aida,Vazquez, Alfredo
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- An N-heterocyclic carbene as a nucleophilic catalyst for cyanosilylation of aldehydes
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The first method for cyanosilylation of aldehydes with trimethylsilyl cyanide in the presence of the N-heterocyclic carbene prepared from 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride and potassium tert-butoxide, as a nucleophilic catalyst, is described. Georg Thieme Verlag Stuttgart.
- Fukuda, Yoshimasa,Maeda, Yuka,Ishii, Satoru,Kondo, Kazuhiro,Aoyama, Toyohiko
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- P(MeNMCH2CH2)3N: An effective catalyst for trimethylsilycyanation of aldehydes and ketones
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The title non-ionic phosphazane base promotes the trimethylsilycyanation of alkyl and alkyl aldehydes and ketones in moderate to high yields at room temperature. 29Si-NMR spectral evidence for the intermediacy of a phosphazane phosphorus-silicon adduct is presented.
- Wang, Zhigang,Fetterly, Brandon,Verkade, John G
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- Lanthanoid(III) Alkoxides as Novel Catalysts for a Rapid Transhydrocyanation from Acetone Cyanohydrin to Aldehydes and Ketones
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A rapid transhydrocyanation from acetone cyanohydrin to several aldehydes and ketones is promoted by a catalytic amount of lanthanoid(III) alkoxide to provide the corresponding cyanohydrins.
- Ohno, Hiroshi,Mori, Atsunori,Inoue, Shohei
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- Enantioselective cyanosilylation of aldehydes catalysed by a diastereomeric mixture of atropisomeric thioureas
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New bifunctional atropisomeric thioureas 1 were synthesised and tested as both a mixture of diastereomers (aR/aS)-(R,R)-1 and as single diastereomers (aR)-(R,R)-1 and (aR)-(S,S)-1, in the organocatalysed, enantioselective, cyanosilylation of a range of al
- Steele, Rebecca M.,Monti, Chiara,Gennari, Cesare,Piarulli, Umberto,Andreoli, Federico,Vanthuyne, Nicolas,Roussel, Christian
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- Highly enantioselective cyanosilylation of aldehydes catalyzed by a chiral oxazaborolidinium ion
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The chiral oxazaborolidinium salts 1 and 2 are excellent catalysts for the enantioselective cyanosilylation of a wide variety of aldehydes (see Table 1) using trimethylsilyl (TMS) cyanide and triphenylphosphine oxide as the source of a new reactive cyanide donor. This donor appears to be the isocyanophosphorane Ph3P(OTMS)(N=C:) (4). The novel process described herein has several advantages: predictability of absolute configuration of cyanohydrin products from a mechanistic model (3), high yields and very good enantiomeric purity of products (≥90%), and, finally, easy and efficient recovery of the catalytic ligand. Copyright
- Ryu, Do Hyun,Corey
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- BMPD, a novel C2-chiral 1,3-diketone ligand; synthesis and application to an asymmetric catalytic reaction
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The synthesis of BMPD, 1,3-bis(2-methylferrocenyl)-propane-1,3-dione, was achieved via the Claisen condensation of a homochiral ferrocenecarboxylate and an acetylferrocene derived from the same chiral formylferrocene. Several metal complexes were prepared to exemplify the complexation ability of BMPD. A BMPD-yttrium complex was found to act as a new catalyst for silylcyanation of aldehydes with remarkable efficiency. As little as 0.2 mol% of the complex catalyzed the reaction of benzaldehyde and cyanotrimethylsilane to afford the cyanohydrin in 95% yield with 87% ee.
- Abiko, Atsushi,Wang, Guo-Qiang
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- Preparation of polystyrene-bound dichlorotitanium dialkoxide and its application as a polymer-supported Lewis acid catalyst in organic syntheses
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Polymer-supported dichlorotitanium dialkoxide was readily prepared from polystyrene-bound α-glycol and dichlorotitanium diisopropoxide. When we employed it as an immobilized Lewis acid catalyst, several fundamental and important Lewis acid-catalyzed react
- Fujita, Ken-Ichi,Muraki, Takahito,Hashimoto, Shigeru,Oishi, Akihiro,Taguchi, Yoichi
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- 1,2-Diphenylethylenediamine linked chiral Ti(IV) complex - A new entry to the highly enantioselective silylcyanation of aliphatic and aromatic aldehydes
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Highly enantioselective silylcyanation of aliphatic and aromatic aldehydes was achieved by using a 1,2-diphenylethylenediamine linked chiral Ti(IV) complex as the catalyst.
- Chang, Chun-Wei,Yang, Chun-Tzu,Hwang, Chyuan-Der,Uang, Biing-Jiun
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- Br?nsted Acid-Catalyzed Cyanotritylation of Aldehydes by Trityl Isocyanide
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Cyanohydrins are versatile intermediates toward valuable organic compounds like α-hydroxy carboxylic acids, α-amino acids, and β-amino alcohols. Numerous protocols are available for synthesis of (O-protected) cyanohydrins, but all procedures invariably rely on the use of toxic cyanide sources. A novel cyanide-free synthesis of O-trityl protected cyanohydrins via a catalytic Passerini-type reaction involving aldehydes and trityl isocyanide is reported. The feasibility of a catalytic asymmetric reaction is demonstrated using chiral phosphoric acid catalysis.
- Cioc, Rǎzvan C.,Schuckman, Peter,Preschel, Hans D.,Vlaar, Tj?stil,Ruijter, Eelco,Orru, Romano V.A.
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- Asymmetric Hydrocyanation of Aldehydes Using Chiral Titanium Reagents
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Two highly enantioselective methods for hydrocyanation of aldehydes were developed by using chiral alkoxytitanium reagents.Treatment of benzaldehyde with cyanotrimethylsilane in the presence of a chiral alkoxytitanium affords mandelonitrile in good chemic
- Minamikawa, Hiroyuki,Hayakawa, Satoshi,Yamada, Tohru,Iwasawa, Nobuharu,Narasaka, Koichi
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- Enantioselective silylcyanation of aldehydes catalyzed by new chiral oxovanadium complex
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Oxovanadium(V) complex 4 was prepared from VOSO4 and tridentate Schiff base ligand, which was prepared from substituted salicylaldehyde and inexpensive (S)-valine. Asymmetric silylcyanation of the aldehydes catalyzed by catalyst 4 afforded cyanohydrins with good enantioselectivities.
- Chu, Chang-Ying,Hsu, Chu-Tin,Lo, Po Hsiang,Uang, Biing-Jiun
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- Enantioselective Trimethylsilylcyanation of Some Aldehydes by Chiral Titanium Schiff's Base Complexes
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The complexes formed between titanium tetraalkoxide and chiral Schiff's bases make excellent catalysts for enantioselective trimethylsilylcyanation of aldehydes to optically active cyanohydrins in high optical yield.
- Hayashi, Masahiko,Miyamoto, Yasunori,Inoue, Tetsuya,Oguni, Nobuki
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- Enantioconvergent Cu-Catalyzed Radical C-N Coupling of Racemic Secondary Alkyl Halides to Access α-Chiral Primary Amines
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α-Chiral alkyl primary amines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common alkyl halides with ammonia is appealing for potential rapid access to α-chiral primary amines, but has hitherto remained rare due to the multifaceted difficulties in using ammonia and the underdeveloped C(sp3)-N coupling. Here we demonstrate sulfoximines as excellent ammonia surrogates for enantioconvergent radical C-N coupling with diverse racemic secondary alkyl halides (>60 examples) by copper catalysis under mild thermal conditions. The reaction efficiently provides highly enantioenrichedN-alkyl sulfoximines (up to 99% yield and >99% ee) featuring secondary benzyl, propargyl, α-carbonyl alkyl, and α-cyano alkyl stereocenters. In addition, we have converted the masked α-chiral primary amines thus obtained to various synthetic building blocks, ligands, and drugs possessing α-chiral N-functionalities, such as carbamate, carboxylamide, secondary and tertiary amine, and oxazoline, with commonly seen α-substitution patterns. These results shine light on the potential of enantioconvergent radical cross-coupling as a general chiral carbon-heteroatom formation strategy.
- Cheng, Jiang-Tao,Dong, Xiao-Yang,Gu, Qiang-Shuai,Li, Zhong-Liang,Liu, Juan,Liu, Xin-Yuan,Luan, Cheng,Wang, Fu-Li,Wang, Li-Lei,Yang, Ning-Yuan,Zhang, Yu-Feng
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supporting information
p. 15413 - 15419
(2021/09/30)
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- Nickel-Catalyzed, Reductive C(sp3)?Si Cross-Coupling of α-Cyano Alkyl Electrophiles and Chlorosilanes
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A nickel/zinc-catalyzed cross-electrophile coupling of alkyl electrophiles activated by an α-cyano group and chlorosilanes is reported. Elemental zinc is the stoichiometric reductant in this reductive coupling process. By this, a C(sp3)?Si bond can be formed starting from two electrophilic reactants whereas previous methods rely on the combination of carbon nucleophiles and silicon electrophiles or vice versa.
- Oestreich, Martin,Zhang, Liangliang
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supporting information
p. 18587 - 18590
(2021/07/25)
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- A High-Throughput Screening Method for the Directed Evolution of Hydroxynitrile Lyase towards Cyanohydrin Synthesis
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Chiral cyanohydrins are useful intermediates in the pharmaceutical and agricultural industries. In nature, hydroxynitrile lyases (HNLs) are a kind of elegant tool for enantioselective hydrocyanation of carbonyl compounds. However, currently available methods for demonstrating hydrocyanation are still stalled at precise, but low-throughput, GC or HPLC analyses. Herein, we report a chromogenic high-throughput screening (HTS) method that is feasible for the cyanohydrin synthesis reaction. This method was highly anti-interference and sensitive, and could be used to directly profile the substrate scope of HNLs either in cell-free extract or fermentation clear broth. This HTS method was also validated by generating new variants of PcHNL5 that presented higher catalytic efficiency and stronger acidic tolerance in variant libraries.
- Zheng, Yu-Cong,Ding, Liang-Yi,Jia, Qiao,Lin, Zuming,Hong, Ran,Yu, Hui-Lei,Xu, Jian-He
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p. 996 - 1000
(2021/01/15)
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- CO2-Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**
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Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2-mediated selective cyanohydrin synthesis was further showcased by broadening Kiliani–Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl- and arylaldehydes, KCN and an atmospheric pressure of CO2.
- Juhl, Martin,Petersen, Allan R.,Lee, Ji-Woong
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supporting information
p. 228 - 232
(2020/11/30)
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- OXAZOLE AND THIAZOLE DERIVATIVES AS INHIBITORS OF ASK1
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The present technology is directed to compounds of formula (I), compositions thereof, and methods related to inhibition of ASKI. In particular, the present compounds and compositions may be used to treat ASKl-mediated disorders and conditions, including,
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Paragraph 0129
(2019/06/09)
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- Visible-Light-Driven N-Heterocyclic Carbene Catalyzed γ- and ?-Alkylation with Alkyl Radicals
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The merging of photoredox catalysis and N-heterocyclic carbene (NHC) catalysis for γ- and ?-alkylation of enals with alkyl radicals was developed. The alkylation reaction of γ-oxidized enals with alkyl halides worked well for the synthesis γ-multisubstituted-α,β-unsaturated esters, including those with challenging vicinal all-carbon quaternary centers. The synthesis of ?-multisubstituted-α,β-γ,δ-diunsaturated esters by an unprecedented NHC-catalyzed ?-functionalization was also established.
- Dai, Lei,Xia, Zi-Hao,Gao, Yuan-Yuan,Gao, Zhong-Hua,Ye, Song
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supporting information
p. 18124 - 18130
(2019/11/13)
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- Method for synthesizing alkyne through catalytic asymmetric cross coupling (by machine translation)
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The invention belongs to the field of, asymmetric synthesis, and discloses a method for catalyzing asymmetric cross- coupling to synthesize: an alkyne, and the L method comprises, the following steps, of A: preparing B a cuprous, salt and C a: ligand; preparing a catalyst; adding a base; reacting the compound with the compound with the compound; and reacting the compound with the compound. Of these, one of them, X is selected from the group consisting of, R halogens. 1 Optionally substituted heteroarylsulfonylcyanamide groups selected from the, group consisting, of optionally substituted, phenyl groups In-flight vehicle, R6 Trialkyl silyl groups or alkyl radicals, R2 Cycloalkyl radicals optionally substituted with an, optionally substituted alkyl, (CH radical2 )n R4 Multi,layer chain, n=0-10,R saw blade4 A group selected, from, the group consisting of phenyl, alkenyl, aralkynyls, noonyloxy,and, noonylsulfonylsulfonylsulfonylsulfonylsulfonylsulfonylsulfonylsulfonylsulfonylsulphonylsulphonylsulphonylsulphonylsulphonylsulphonylsulphonylsulphonylsulphonylsulphonylphenyl disiloxy-radicals. R3 A ligand, selected from hydrogen or any of the functional groups, is selected from the group consisting of, hydrogen and any L other functional group. The method, R disclosed by the, A invention has the, advantages of good catalytic, R ’ effect, wide application range. and high catalytic efficiency, and the, method disclosed by the, invention has the. advantages of good catalytic effect, wide application range and high catalytic efficiency. (by machine translation)
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Paragraph 0414-0415
(2020/01/12)
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- Acceptorless and Base-free Dehydrogenation of Cyanohydrin with (η6-Arene)halide(Bidentate Phosphine)ruthenium(II) Complex
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Ruthenium-catalyzed dehydrogenation of cyanohydrins under acceptorless and base-free conditions was demonstrated for the first time in the synthesis of acyl cyanide. As opposed to the thermodynamically preferred elimination of hydrogen cyanide, the dehydrogenation of cyanohydrins could be kinetically controlled with ruthenium (II) bidentate phosphine complexes. The effects of the arene, phosphine ligands and counter anions were investigated in regard to catalytic activity and selectivity. Selective dehydrogenation can occur via β-hydride elimination with the experimentally observed [(alkoxide)Ru] complex. (Figure presented.).
- Kim, Kicheol,Moeljadi, Adhitya Mangala Putra,Hirao, Hajime,Hong, Soon Hyeok
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supporting information
p. 3292 - 3298
(2017/09/06)
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- Enantioselective cyanosilylation of aldehydes catalyzed by a multistereogenic salen-Mn(III) complex with a rotatable benzylic group as a helping hand
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A multistereogenic salen-Mn(iii) complex bearing an aromatic pocket and two benzylic groups as helping hands was found to be efficient in the catalysis of asymmetric cyanosilylation. The salen-Mn catalyst partially mimics the functions of biocatalysts by
- Wei, Yun-Long,Huang, Wei-Sheng,Cui, Yu-Ming,Yang, Ke-Fang,Xu, Zheng,Xu, Li-Wen
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p. 3098 - 3103
(2015/02/02)
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- Enantioselective cyanosilylation of aldehydes catalyzed by novel camphor derived Schiff bases-titanium(IV) complexes
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Five tridentate Schiff bases have been prepared from (1R,2S,3R,4S)-3-amino- 1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and salicylaldehydes. X-ray structure investigation revealed differences in their molecular conformation, and their titanium(IV) complexes
- B?ocka, Ewelina,Bosiak, Mariusz J.,We?niak, Miros?aw,Ludwiczak, Agnieszka,Wojtczak, Andrzej
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p. 554 - 562
(2014/05/06)
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- Catalytic asymmetric synthesis of secondary nitriles via stereoconvergent negishi arylations and alkenylations of racemic α-bromonitriles
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The first method for the stereoconvergent cross-coupling of racemic α-halonitriles is described, specifically, nickel-catalyzed Negishi arylations and alkenylations that furnish an array of enantioenriched α-arylnitriles and allylic nitriles, respectively. Noteworthy features of this investigation include: the highly enantioselective synthesis of α-alkyl-α-aryl nitriles that bear secondary α-alkyl substituents; the first examples of the use of alkenylzinc reagents in stereoconvergent Negishi reactions of alkyl electrophiles; demonstration of the utility of a new family of ligands for asymmetric Negishi cross-couplings (a bidentate bis(oxazoline), rather than a tridentate pybox); in the case of arylzinc reagents, carbon-carbon bond formation at a remarkably low temperature (-78 °C), the lowest reported to date for an enantioselective cross-coupling of an alkyl electrophile; a mechanistic dichotomy between Negishi reactions of an unactivated versus an activated secondary alkyl bromide.
- Choi, Junwon,Fu, Gregory C.
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supporting information; experimental part
p. 9102 - 9105
(2012/07/13)
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- Silylcyanation of aldehydes, ketones, and imines catalyzed by a 6,6'-bis-sulfonamide derivative of 7,7'-dihydroxy-8,8'-biquinolyl (azaBINOL)
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6,6'-Bis(methylaminosulfonyl)-7,7'-dihydroxy-8,8'-biquinolyl (3) catalyzes (5-10 mol-%) the addition of trimethylsilyl cyanide to aldehydes (aryl, alkyl, and α,β-unsaturated; 42-92 % yields), ketones (aryl alkyl, dialkyl; 22-82 % yields), and N-benzylaldimines (14-78 % yields) in toluene (0 °C or room temp.) to give the expected cyanohydrin and Strecker adducts following desilylation. Among a series of closely related compounds lacking any one of their defining structural features, bis-sulfonamide 3 and its N,N'-dimethyl derivative are exceptional in catalyzing the silylcyanation of benzaldehyde in the absence of all other additives. Hammett analysis of the competitive silylcyanation of para-substituted benzaldehydes catalyzed by 3 showed a linear free-energy relationship (R2 = 0.928) with a modest positive reaction constant (ρ = +1.52). X-ray diffraction analysis of (±)-3 indicated a cisoid biaryl conformation and the existence of an intramolecular hydrogen bond between C7'-OH and C7-O. Resolution of (±)-3 was achieved by HPLC separation of its tetravalerate derivative on a chiral stationary phase. The absolute configurations of the optical isomers of 3 were assigned by correlation of the ECD spectra with those of related biquinolyls of known configuration. The silylcyanation of aldehydes catalyzed by (-)-(aR)-3 leads to cyanohydrins with a preference for the (S)-configured product with an ee of 10 %. The organocatalytic action of 3 is ascribed to hydrogen bonding and Bronsted acid catalysis effects that are dependent on its acidifying sulfonamide groups, general base capability, and interannular proximity effects made possible by the biaryl structure. Copyright
- Sephton, Selena Milicevic,Wang, Chao,Zakharov, Lev N.,Blakemore, Paul R.
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experimental part
p. 3249 - 3260
(2012/08/08)
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- Redox-neutral α-cyanation of amines
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α-Aminonitriles inaccessible by traditional Strecker chemistry are obtained in redox-neutral fashion by direct amine α-cyanation/N-alkylation or alternatively, α-aminonitrile isomerization. These unprecedented transformations are catalyzed by simple carboxylic acids.
- Ma, Longle,Chen, Weijie,Seidel, Daniel
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supporting information
p. 15305 - 15308
(2012/10/29)
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- PYRIDO PYRIMIDINES
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Compounds of formula and pharmaceutically acceptable salts thereof are described, as well as the pharmaceutical compositions containing said compounds and their pharmaceutically acceptable salts, and the use of said compounds and pharmaceutical compositions for the treatment, control or amelioration of proliferative diseases, including cancer, Down syndrome or early onset Alzheimer's disease.
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Page/Page column 110
(2012/07/28)
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- Cooperative thiourea-Bronsted acid organocatalysis: Enantioselective cyanosilylation of aldehydes with TMSCN
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We report a new thiourea - Bronsted acid cooperative catalytic system for the enantioselective cyanosilylation of aldehydes with yields up to 90% and enantioselectivities up to 88%. The addition of an achiral acid was found to be crucial for high asymmetric induction. Mechanistic investigations using a combination of NMR, ESI-MS, and density functional theory computations (including solvent corrections) at the M06/6-31G(d,p) level of theory suggest that the key catalytic species results from the cooperative interaction of bifunctional thioureas and an achiral acid that form well-defined chiral hydrogen-bonding environments.
- Zhang, Zhiguo,Lippert, Katharina M.,Hausmann, Heike,Kotke, Mike,Schreiner, Peter R.
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experimental part
p. 9764 - 9776
(2012/01/03)
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- α-Pinene-type chiral Schiff bases as tridentate ligands in asymmetric addition reactions
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A group of tridentate Schiff bases derived from (+)-α-pinene were synthesized. The steric effects in the transition state, the importance of π-π stacking interactions as well as the electronic effects of aryl aldehydes according to Hammett constant values in the enantioselective addition of Et2Zn to aldehydes with the use of Schiff bases as chiral ligands are described. Also, a variety of aldehydes were cyanated using a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. The influence of a conjugated double-bond in the cyanation substrates on enantioselectivity was observed. The chemical structures of the chiral Schiff base-titanium alkoxide complexes are discussed based on their 1H and 13C NMR spectra. 3D models of the Zn2-complex catalyst and Ti-complex catalyst containing α-pinane-type Schiff bases based on X-ray diffraction experiments are postulated. The models presented were consistent with the reported chirality of the addition product and observed ee.
- Jaworska, Magdalena,Blocka, Ewelina,Kozakiewicz, Anna,Welniak, Miroslaw
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experimental part
p. 648 - 657
(2011/07/08)
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- Enzymatic kinetic resolution of racemic cyanohydrins via enantioselective acylation
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Enzymatic kinetic resolution of a series of aromatic and aliphatic cyanohydrins in organic media has been investigated. The behavior of potential lipases, molecular sieves, acyl reagent, reaction temperature, and organic solvents on the kinetic resolution was studied. The influence of substrate structure, steric, and electronic nature and position of the aryl substituent on the enantioselectivity was discussed. Under the optimized reaction conditions, good enantioselectivity could be achieved for most of the investigated compounds. Specifically, substrates 1a, 1c, 1d, 1f, 1u could be resolved with the kinetic enantiomer ratio (E) higher than 200.
- Xu, Qing,Xie, Yongli,Geng, Xiaohong,Chen, Peiran
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supporting information; experimental part
p. 624 - 630
(2010/09/07)
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- Room-temperature synthesis of enantioenriched non-protected cyanohydrins using vanadium(salalen) catalyst
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Room-temperature synthesis of enantioenriched non-protected cyanohydrins using acetone cyanohydrin as the cyanide source was achieved by V(salalen) catalyst. Aliphatic aldehydes underwent the cyanation with 89-95% ee in the presence of only 0.2-0.4 mol% catalyst. Aromatic cyanohydrins were also obtained in high enantiomeric excesses under modified conditions.
- Sakai, Yoshifumi,Mitote, Junko,Matsumoto, Kazuhiro,Katsuki, Tsutomu
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scheme or table
p. 5787 - 5789
(2010/09/05)
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- Dibutyltin dimethoxide-catalyzed cyano transfer to aldehydes and imines
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A novel reaction involving cyano transfer from benzophenone cyanohydrin to aldehydes and imines was realized by using dibutyltin dimethoxide as a catalyst. Various cyanohydrins and α-amino nitriles were obtained in moderate to high yields by this reaction. Ketimines also showed remarkable reactivity as cyano acceptors under conventional reaction conditions. This catalytic reaction was further applied to a three-component condensation reaction of aldehydes, aniline, and benzophenone cyanohydrin in the presence of Drierite. Copyright
- Yanagisawa, Akira,Matsumoto, Takuya,Kushihara, Naoyuki,Yoshida, Kazuhiro
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experimental part
p. 2918 - 2922
(2011/01/05)
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- ANTI VIRAL COMPOUNDS
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There is provided small molecule anti-human immunodeficiency virus (anti-HIV) compounds as well as a phenotypic cell-based high throughput screening (HTS) assay for their identification.
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Page/Page column 156
(2010/05/13)
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- Cyanosilylation of aldehydes and ketones catalyzed by nanocrystalline magnesium oxide
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Cyanosilylation of various aldehydes and ketones with TMSCN proceeded smoothly under mild conditions to give the corresponding cyanohydrin trimethylsilyl ethers in the presence of nanocrystalline magnesium oxide. The cyanohydrin trimethylsilyl ethers of aldehydes produced cyanohydrins in good to high yields on treatment with 2 N HCl. 29Si NMR spectral evidence proved that the reaction proceeds through the hypervalent silicate species by coordination to O2-/O- (Lewis basic site) of nanocrystalline magnesium oxide. Copyright Taylor & Francis Group, LLC.
- Lakshmi Kantam,Mahendar, Koosam,Sreedhar, Bojja,Vijay Kumar,Choudary
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experimental part
p. 3919 - 3936
(2009/04/11)
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- Vanadium-catalyzed asymmetric transcyanation of aliphatic aldehydes with acetone cyanohydrin
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The vanadium(V)(salalen) complex prepared in situ from the corresponding vanadium(IV) complex 4 under aerobic conditions was found to be an excellent catalyst for asymmetric transcyanation of aliphatic aldehydes with acetone cyanohydrin as the cyanide sou
- Takaki, Junko,Egami, Hiromichi,Matsumoto, Kazuhiro,Saito, Bunnai,Katsuki, Tsutomu
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p. 502 - 503
(2008/09/21)
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- [Ru(phgly)2(binap)]/Li2CO3: A Highly Active, Robust, and Enantioselective Catalyst for the Cyanosilylation of Aldehydes
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The right combination: A series of aromatic, heteroaromatic, aliphatic, and α,β-unsaturated aldehydes can be converted into the desired silylated cyanohydrins by reaction with (CH3)3SiCN and a catalyst system consisting of the combination of a chiral ruthenium complex and Li2CO3 (see scheme). The reaction is highly enantioselective and affords the R products with up to 98% ee within 24 h at a substrate-tocatalyst ratio of 10000:1. (Chemical Equation Presented).
- Kurono, Nobuhito,Arai, Kenta,Uemura, Masato,Ohkuma, Takeshi
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supporting information; experimental part
p. 6643 - 6646
(2009/03/12)
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- SOLUBLE EPOXIDE HYDROLASE INHIBITORS
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Disclosed are alpha keto amide and alpha hydroxy amide compounds and compositions that inhibit soluble epoxide hydrolase (sEH), methods for preparing the compounds and compositions, and methods for treating patients with such compounds and compositions. The compounds, compositions, and methods are useful for treating a variety of sEH mediated diseases, including hypertensive, cardiovascular, inflammatory, pulmonary, and diabetic-related diseases.
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Page/Page column 114-115
(2008/12/06)
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- Purification and characterization of a novel (R)-hydroxynitrile lyase from Eriobotrya japonica (Loquat)
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A hydroxynitrile lyase was isolated and purified to homogeneity from seeds of Eriobotrya japonica (loquat). The final yield, of 36% with 49-fold purification, was obtained by 30-80% (NH4)2SO4 fractionation and column chromatography on DEAE-Toyopearl and Concanavalin A Sepharose 4B, which suggested the presence of a carbohydrate side chain. The purified enzyme was a monomer with a molecular mass of 72 kDa as determined by gel filtration, and 62.3 kDa as determined by SDS-gel electrophoresis. The N-terminal sequence is reported. The enzyme was a flavoprotein containing FAD as a prosthetic group, and it exhibited a Km of 161 μM and a k cat/Km of 348 s-1 mM-1 for mandelonitrile. The optimum pH and temperature were pH 5.5 and 40°C respectively. The enzyme showed excellent stability with regard to pH and temperature. Metal ions were not required for its activity, while activity was significantly inhibited by CuSO4, HgCl2, AgNO3, FeCl3, β-mercaptoethanol, iodoacetic acid, phenylmethylsulfonylfluoride, and diethylpyrocarbonate. The specificity constant (kcat/Km) of the enzyme was investigated for the first time using various aldehydes as substrates. The enzyme was active toward aromatic and aliphatic aldehydes, and showed a preference for smaller substrates over bulky one.
- Ueatrongchit, Techawaree,Kayo, Ai,Komeda, Hidenobu,Asano, Yasuhisa,H-Kittikun, Aran
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p. 1513 - 1522
(2008/12/21)
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- An efficient new synthesis of racemic cetiedil and a novel route to α-ketocarboxylic acids utilising mild conditions
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We describe a new efficient synthesis of the prescribed racemic drug cetiedil [(±)-2-cyclohexyl-2-(3-thienyl)ethanoic acid 2-(hexahydro-1H-azepin-1-yl)ethylester], Additionally, we report herein a high yielding large scale, route to its acid precursor 7, subsequently enabling large-scale synthesis of the chiral forms of cetiedil, and detailed pharmacological investigations. Additionally, we describe a novel route to α-ketocarboxylic acids, starting from readily available or easily obtainable aldehydes: The mild conditions utilised opens up its applicability for use on molecules of biological interest. Georg Thieme Verlag Stuttgart.
- Roxburgh, Craig J.,Ganellin, C. Robin,Thorpe, Andrew J.
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p. 1211 - 1214
(2008/02/07)
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- Chiral Pt(II)/Pd(II) pincer complexes that show C-H?Cl hydrogen bonding: Synthesis and applications to catalytic asymmetric aldol and silylcyanation reactions
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A chiral C2-symmetric NCN ligand, (5R,7R)-1,3-bis(6,6-dimethyl-5,6,7,8-tetrahydro-5,7-methanoquinolin-2-yl)benzene has been synthesized. A direct cyclometalation of this ligand with K2MCl4 (M = Pt, Pd) in dry acetic acid offered the corresponding pincer complexes, [(5R,7R)-1,3-bis(6,6-dimethyl-5,6,7,8-tetrahydro-5,7-methanoquinolin-2-yl)phenyl]platinum(II) chloride 5a and its palladium(II) analogue 5b. The Pt(II) and Pd(II) complexes 5 were characterized by NMR spectroscopy, and X-ray crystal structure analysis was done for the Pt(II) complex. The NMR data for both the complexes and X-ray crystal structural data for the chloro-Pt(II) complex indicate the existence of intramolecular C-H?Cl hydrogen bonding both in solution and in solid states. Chloride abstraction from 5a by treatment with silver triflate resulted in the corresponding triflate complex 6a, which generates the corresponding cationic aqua complex 7a in the presence of water molecules. The Pt(II) complex 6a/7a was used as asymmetric catalyst in the aldol reaction between methyl isocyanoacetate and aldehydes and also in the silylcyanation of aldehydes.
- Yoon, Myeong Sik,Ramesh, Rengan,Kim, Jeongryul,Ryu, Dowook,Ahn, Kyo Han
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p. 5939 - 5946
(2007/10/03)
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- Synthesis of the bifunctional BINOL ligands and their applications in the asymmetric additions to carbonyl compounds
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Efficient one-step syntheses of the bifunctional BINOL and H8BINOL ligands (S)-6 and (S)-8 have been developed from the reaction of BINOL and H8BINOL with morpholinomethanol, respectively. The X-ray analyses of these compounds have revealed their structural similarity and difference. The bifunctional H8BINOL (S)-8 is found to be highly enantioselective for the reaction of diphenylzinc with many aliphatic and aromatic aldehydes and especially is the most enantioselective catalyst for linear aliphatic aldehydes. Unlike other catalysts developed for the diphenylzinc addition which often require the addition of a significant amount of diethylzinc with cooling (or heating) the reaction mixture in order to achieve high enantioselectivity, using (S)-8 needs no additive and gives excellent results at room temperature. (S)-8 in combination with diethylzinc and Ti(OiPr)4 can catalyze the highly enantioselective phenylacetylene addition to aromatic aldehydes. It can also promote the phenylacetylene addition to acetophenone at room temperature though the enantioselectivity is not very high yet. Without using Ti(OiPr)4 and a Lewis base additive, (S)-8 in combination with diethylzinc can catalyze the reaction of methyl propiolate with an aldehyde to form the highly functional γ-hydroxy-α,β-acetylenic esters except that the enantioselectivity is low at this stage. The bifunctional BINOL ligand (S)-6 in combination with Me2AlCl is found to be a highly enantioselective catalyst for the addition of TMSCN to both aromatic and aliphatic aldehydes.
- Qin, Ying-Chuan,Liu, Lan,Sabat, Michal,Pu, Lin
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p. 9335 - 9348
(2007/10/03)
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- An asymmetric, chemo-enzymatic synthesis of O-acetylcyanohydrins
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A one-pot chemo-enzymatic synthesis of highly enantiomerically enriched O-acetylcyanohydrins has been developed. The bimetallic (salen)titanium complex 1 is used to convert aldehydes into nonracemic (R)-O-acetylcyanohydrins with 61 to 93 % enantiomeric ex
- Belokon, Yuri N.,Blacker, A. John,Clutterbuck, Lisa A.,Hogg, David,North, Michael,Reeve, Christopher
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p. 4609 - 4617
(2007/10/03)
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- INHIBITORS OF AKT ACTIVITY
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Invented are novel 1 H-imidazo[4,5-c]pyridin-2-yl compounds, the use of such compounds as inhibitors of protein kinase B activity and in the treatment of cancer and arthritis.
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Page/Page column 112-113
(2008/06/13)
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- A new (R)-hydroxynitrile lyase from Prunus mume: Asymmetric synthesis of cyanohydrins
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A new hydroxynitrile lyase (HNL) was isolated from the seed of Japanese apricot (Prunus mume). The enzyme has similar properties with HNL isolated from other Prunus species and is FAD containing enzyme. It accepts a large number of unnatural substrates (benzaldehyde and its variant) for the addition of HCN to produce the corresponding cyanohydrins in excellent optical and chemical yields. A new HPLC based enantioselective assay technique was developed for the enzyme, which promotes the addition of KCN to benzaldehyde in a buffered solution (pH=4.5).
- Nanda, Samik,Kato, Yasuo,Asano, Yasuhisa
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p. 10908 - 10916
(2007/10/03)
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- P(RNCH2CH2)N: Efficient catalysts for the cyanosilylation of aldehydes and ketones
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The 1,2-addition of trialkylsilylcyanides to aldehydes and ketones produces the corresponding protected cyanohydrins in good to excellent yields when carried out at 0°C to room temperature in the presence of catalytic amounts of the nonionic strong base P(RNCH2CH2)N (R = Me, i-Pr) in THF. These catalysts are easily removed from the product by hydrolysis or column filtration through silica gel.
- Fetterly, Brandon M.,Verkade, John G.
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p. 8061 - 8066
(2007/10/03)
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- Guanidine-catalyzed asymmetric trimethylsilylcyanation of carbonyl compounds
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Several kinds of modified guanidines were applied to the trimethylsilylcyanation of 3-phenylpropanal, cylohexanecarboxaldehyde, pivalaldehyde, and 4-phenyl-2-butanone. Good to moderate enantioselectivity was obtained, even on a ketonic substrate, when a C
- Kitani, Yukari,Kumamoto, Takuya,Isobe, Toshio,Fukuda, Keiko,Ishikawa, Tsutomu
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p. 1653 - 1658
(2007/10/03)
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- O-Protected 3-hydroxy-oxazolidin-2,4-diones: Novel precursors in the synthesis of α-hydroxyhydroxamic acids
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O-Protected 3-hydroxyoxazolidin-2,4-diones have been prepared in a novel one-pot reaction by subsequent treatment of cyanohydrins with 1,1′-carbonyldiimidazole and O-protected hydroxylamines followed by acidic hydrolysis of the intermediate 4-imino-oxazolidin-2-ones. Decarbonylation of O-protected 3-hydroxyoxazolidin-2,4-diones by catalytic amounts of sodium methoxide, lithium hydroxide, sodium carbonate and caesium carbonate in methanol afforded O-protected α-hydroxyhydroxamic acids in excellent yields. Their deprotection provided a series of novel α-hydroxyhydroxamic acids.
- Kurz, Thomas,Widyan, Khalid
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p. 2023 - 2027
(2007/10/03)
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- Cyanobenzoylation and hydrocyanation of aldehydes with benzoyl cyanide using no catalyst
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(Matrix presented) In the presence of MS 4A in DMSO, cyanobenzoylation of various aldehydes with benzoyl cyanide proceeded very smoothly to give the corresponding cyanohydrin benzoates in high to excellent yields without an acid or a base. On the other hand, reaction of aldehydes with BzCN in DMSO-H2O also occurred readily to afford the corresponding free cyanohydrins exclusively.
- Watahiki, Tsutomu,Ohba, Sayoko,Oriyama, Takeshi
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p. 2679 - 2681
(2007/10/03)
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