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Catalytic Enantioselective Reaction of α‐Phenylthioacetonitriles with Imines Using Chiral Bis(imidazoline)–Palladium Catalysts 下载免费PDF全文
Masaru Kondo Natsumi Kobayashi Prof. Dr. Tsubasa Hatanaka Prof. Dr. Yasuhiro Funahashi Prof. Dr. Shuichi Nakamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(25):9066-9070
The catalytic enantioselective reaction of α‐phenylthioacetonitriles with imines has been developed. The reaction of various imines proceeds in good yields and diastereo‐ and enantioselectivities in the presence of chiral bis(imidazoline)–palladium catalysts. The obtained products can be converted into β‐aminonitrile or β‐aminoamide compounds without loss of enantiopurity. 相似文献
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Catalytic Asymmetric Synthesis of 3‐Indolyl Methanamines Using Unprotected Indoles and N‐Boc Imines under Basic Conditions 下载免费PDF全文
Prof. Dr. Takayoshi Arai Junki Kakino 《Angewandte Chemie (International ed. in English)》2016,55(49):15263-15267
A chiral imidazolidine‐containing NCN/Pd‐OTf catalyst ( C4 ) promoted the nucleophilic addition of unprotected indoles to N‐Boc imines. Using sulfinyl amines as the N‐Boc imine precursors, the combined use of C4 with K2CO3 activated the NH indoles to give chiral 3‐indolyl methanamines with up to 98 % ee. Compared with conventional acid‐catalyzed Friedel–Crafts reactions, this reaction proceeds under mildly basic conditions and is advantageous for the use of acid‐sensitive substrates. 相似文献
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Dr. Sukalyan Bhadra Prof. Dr. Hisashi Yamamoto 《Angewandte Chemie (International ed. in English)》2016,55(42):13043-13046
Direct asymmetric synthesis of N‐chiral amine oxides was accomplished (up to 91:9 e.r.) by means of a bimetallic titanium catalyst. A hydroxy group situated at the γ‐position of the N stereocenter enables the desired N‐oxidation through dynamic kinetic resolution of the trivalent amine substrates. The method was further extended to the kinetic resolution of racemic γ‐amino alcohols with a preexisting stereocenter, giving an important class of enantioenriched (up to 99.9:0.1 e.r.) building blocks that are otherwise difficult to synthesize. 相似文献
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Taichi Kano Dr. Yukako Yamaguchi Keiji Maruoka Prof. 《Angewandte Chemie (International ed. in English)》2009,48(10):1838-1840
The moderate nucleophilicity of the axially chiral amino sulfonamide (S)‐ 1 suppresses the problematic side reactions, including aldol reactions, in the asymmetric Mannich reaction of N‐Boc‐protected imines with aldehydes. The corresponding adducts are obtained in good yield and excellent stereoselectivity (see scheme; Boc=tert‐butoxycarbonyl, Tf=trifluoromethanesulfonyl).
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Wee Shan Tay Dr. Yunpeng Lu Dr. Xiang-Yuan Yang Dr. Yongxin Li Dr. Sumod A. Pullarkat Prof. Pak-Hing Leung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(48):11308-11317
Synthetic challenges have significantly slowed the development of the catalytic asymmetric hydroarsination reaction despite it being a highly attractive C−As bond formation methodology. In addition, there is a poor understanding of the main reaction steps in such reactions which limit further development in the field. Herein, key intermediates of the hydroarsination reaction catalyzed by a PCP NiII-Cl pincer complex are presented upon investigating the reaction with DFT calculations, conductivity measurements, NMR spectroscopy, and catalytic screening. The novel Ni–Cl–As interaction proposed was then contrasted against known NiII-catalyzed hydrophosphination reactions to highlight dissimilarities between them even though P and As share a close group relationship. Lastly, the asymmetric hydroarsination of nitroolefins was further developed to furnish a library of chiral organoarsines in up to 99 % yield and 80 % ee under mild conditions (−20 °C to RT) between 5 to 210 mins. 相似文献
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Catalytic Enantioselective Reaction of α‐Aminoacetonitriles Using Chiral Bis(imidazoline) Palladium Catalysts 下载免费PDF全文
Masaru Kondo Tomoki Nishi Prof. Dr. Tsubasa Hatanaka Prof. Dr. Yasuhiro Funahashi Prof. Dr. Shuichi Nakamura 《Angewandte Chemie (International ed. in English)》2015,54(28):8198-8202
The catalytic enantioselective reaction of diphenylmethylidene‐protected α‐aminoacetonitriles with imines has been developed. Good yields and diastereo‐ and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts. The reaction of α‐aminonitriles with di‐tert‐butyl azodicarboxylate afforded chiral α,α‐diaminonitriles in high yields with high enantioselectivities. 相似文献
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Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration 下载免费PDF全文
Veronika M. Shoba Dr. Nathan C. Thacker Andrew J. Bochat Prof. Dr. James M. Takacs 《Angewandte Chemie (International ed. in English)》2016,55(4):1465-1469
Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl‐directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime‐directed CAHB of alkyl‐substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime‐containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O‐substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon–carbon coupling reactions, and the preparation of chiral 3,4,4‐trisubstituted isoxazolines. 相似文献
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Carley Chandler Dr. Patrizia Galzerano Anna Michrowska Dr. Benjamin List Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(11):1978-1980
Double‐cross : Proline catalyzes the double Mannich reaction of acetaldehyde with N‐Boc imines in excellent yields (up to 99 %; Boc=tert‐butoxycarbonyl) and close to perfect diastereo‐ and enantioselectivities. Depending on the choice of catalysts, both the chiral, pseudo‐C2‐symmetric diastereomer and the corresponding meso compound can be prepared. Cross double Mannich reactions of acetaldehyde with two different imines are also demonstrated.
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Direct Catalytic Asymmetric Mannich Reaction with Dithiomalonates as Excellent Mannich Donors: Organocatalytic Synthesis of (R)‐Sitagliptin 下载免费PDF全文
Dr. Han Yong Bae Mun Jong Kim Jae Hun Sim Prof. Dr. Choong Eui Song 《Angewandte Chemie (International ed. in English)》2016,55(36):10825-10829
In this study, dithiomalonates (DTMs) were demonstrated to be exceptionally efficient Mannich donors in terms of reactivity and stereoselectivity in cinchona‐based‐squaramide‐catalyzed enantioselective Mannich reactions of diverse imines or α‐amidosulfones as imine surrogates. Owing to the superior reactivity of DTMs as compared to conventional malonates, the catalyst loading could be reduced to 0.1 mol % without the erosion of enantioselectivity (up to 99 % ee). Furthermore, by the use of a DTM, even some highly challenging primary alkyl α‐amidosulfones were smoothly converted into the desired adducts with excellent enantioselectivity (up to 97 % ee), whereas the use of a malonate or monothiomalonate resulted in no reaction under identical conditions. The synthetic utility of the chiral Mannich adducts obtained from primary alkyl substrates was highlighted by the organocatalytic, coupling‐reagent‐free synthesis of the antidiabetic drug (?)‐(R)‐sitagliptin. 相似文献
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Catalytic Asymmetric Mannich Reactions with Fluorinated Aromatic Ketones: Efficient Access to Chiral β‐Fluoroamines 下载免费PDF全文
Barry M. Trost Tanguy Saget Andreas Lerchen Chao‐I Hung 《Angewandte Chemie (International ed. in English)》2016,55(2):781-784
Reported herein is a Zn/Prophenol‐catalyzed Mannich reaction using fluorinated aromatic ketones as nucleophilic partners for the direct enantio‐ and diastereoselective construction of β‐fluoroamine motifs featuring a fluorinated tetrasubstituted carbon. The reaction can be run on a gram scale with a low catalyst loading without impacting its efficiency. Moreover, a related aldol reaction was also developed. Together, these reactions provide a new approach for the preparation of pharmaceutically relevant products possessing tetrasubstituted C? F centers. 相似文献
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Li Huang Dr. Yu Zhang Dr. Richard J. Staples Dr. Rui H. Huang Prof. William D. Wulff 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(17):5302-5313
The catalytic asymmetric aziridination of imines and diazo compounds (AZ reaction) mediated by boroxinate catalysts derived from the VANOL and VAPOL ligands was investigated with chiral imines derived from five different chiral, disubstituted, methyl amines. The strongest matched and mismatched reactions with the two enantiomers of the catalyst were noted with disubstituted methyl amines that had one aromatic and one aliphatic substituent. The synthetic scope for the AZ reaction was examined in detail for α‐methylbenzyl amine for cis‐aziridines from α‐diazo esters and for trans‐aziridines from α‐diazo acetamides. Optically pure aziridines could be routinely obtained in good yields and with high diastereoselectivity and the minor diastereomer (if any) could be easily separated. The matched case for cis‐aziridines involved the (R)‐amine with the (S)‐ligand, but curiously, for trans‐aziridines the matched case involved the (R)‐amine with the (R)‐ligand for imines derived from benzaldehyde and n‐butanal, and the (R)‐amine with the (S)‐ligand for imines derived from the bulkier aliphatic aldehydes pivaldehyde and cyclohexane carboxaldehyde. 相似文献
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Catalytic Asymmetric Mannich‐Type Reaction of N‐Alkylidene‐α‐Aminoacetonitrile with Ketimines 下载免费PDF全文
Shaoquan Lin Dr. Yuji Kawato Dr. Naoya Kumagai Prof. Dr. Masakatsu Shibasaki 《Angewandte Chemie (International ed. in English)》2015,54(17):5183-5186
Optically active vicinal diamines are versatile chiral building blocks in organic synthesis. A soft Lewis acid/hard Brønsted base cooperative catalyst allows for an efficient stereoselective coupling of N‐alkylidene‐α‐aminoacetonitrile and ketimines to access this class of compounds bearing consecutive tetra‐ and trisubstituted stereogenic centers. The strategic use of a soft Lewis basic thiophosphinoyl group for ketimines is the key to promoting the reaction, and aliphatic ketimines serve as suitable substrates with as little as 3 mol % catalyst loading. 相似文献
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《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):63-71
New asymmetric conjugate reduction of β,β‐disubstituted α,β‐unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6‐bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)‐4‐Phenyl‐3‐penten‐2‐one and (E)‐4‐phenyl‐4‐isopropyl‐3‐penten‐2‐one were readily reduced at 60 °C in 95 % ee and 98 % ee, respectively, by 1 mol % of catalyst loading. (EtO)2MeSiH proved to be the best hydrogen donor of choice. tert‐Butyl (E)‐β‐methylcinnamate and β‐isopropylcinnamate could also be reduced to the corresponding dihydrocinnamate derivatives up to 98 % ee. 相似文献