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1.
Dr. Brian N. Laforteza Kelvin S. L. Chan Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2015,54(38):11143-11146
The commonly used para‐nitrobenzenesulfonyl (nosyl) protecting group is employed to direct the C? H activation of amines for the first time. An enantioselective ortho‐C? H cross‐coupling between nosyl‐protected diarylmethylamines and arylboronic acid pinacol esters has been achieved utilizing chiral mono‐N‐protected amino acid (MPAA) ligands as a promoter. 相似文献
2.
Takahiro Horibe Takashi Hazeyama Yuto Nakata Kazuki Takeda Kazuaki Ishihara 《Angewandte Chemie (International ed. in English)》2020,59(39):17256-17260
An enantioselective 1,4‐addition of α,β‐unsaturated carboxylic acids with cycloalkanones has been developed by using chiral amine–boronic acid cooperative catalysts. In the presence of a chiral amine and boronic acid, cycloalkanones and carboxylic acids are activated as chiral enamines and mixed anhydrides, respectively. The corresponding 1,4‐adducts are obtained in high yield with high enantioselectivity. Furthermore, subsequent oxylactonization of the 1,4‐adducts gives spirolactones with high diastereoselectivity. 相似文献
3.
Brian N. Laforteza Kelvin S. L. Chan Jin‐Quan Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(38):11295-11298
The commonly used para‐nitrobenzenesulfonyl (nosyl) protecting group is employed to direct the C H activation of amines for the first time. An enantioselective ortho‐C H cross‐coupling between nosyl‐protected diarylmethylamines and arylboronic acid pinacol esters has been achieved utilizing chiral mono‐N‐protected amino acid (MPAA) ligands as a promoter. 相似文献
4.
Yin Xiao Yong Wang Teng‐Teng Ong Liya Ge Swee Ngin Tan David J. Young T. T. Y. Tan Siu‐Choon Ng 《Journal of separation science》2010,33(12):1797-1805
New single‐isomer, cationic β‐cyclodextrins, including mono‐6‐deoxy‐6‐pyrrolidine‐β‐cyclodextrin chloride (pyCDCl), mono‐6‐deoxy‐6‐(N‐methyl‐pyrrolidine)‐β‐cyclodextrin chloride (N‐CH3‐pyCDCl), mono‐6‐deoxy‐6‐(N‐(2‐hydroxyethyl)‐pyrrolidine)‐β‐cyclodextrin chloride (N‐EtOH‐pyCDCl), mono‐6‐deoxy‐6‐(2‐hydroxymethyl‐pyrrolidine)‐β‐cyclodextrin chloride (2‐MeOH‐pyCDCl) were synthesized and used as chiral selectors in capillary electrophoresis for the enantioseparation of carboxylic and hydroxycarboxylic acids and dansyl amino acids. The unsubstituted pyCDCl exhibited the greatest resolving ability. Most analytes were resolved over a wide range of pH from 6.0 to 9.0 with this chiral selector. In general, increasing pH led to a decrease in resolution. The effective mobilities of all the analytes were found to decrease with increasing CD concentration. The optimal concentration for most carboxylic acids and dansyl amino acid was in the range 5–7.5 mM and >15 mM for hydroxycarboxylic acids. 1H NMR experiments provided direct evidence of inclusion in the CD cavity. 相似文献
5.
Chiral Bifunctional Phosphine‐Carboxylate Ligands for Palladium(0)‐Catalyzed Enantioselective C−H Arylation
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Dr. Lei Yang Dr. Markus Neuburger Prof. Dr. Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2018,57(5):1394-1398
Previous enantioselective Pd0‐catalyzed C?H activation reactions proceeding via the concerted metalation‐deprotonation mechanism employed either a chiral ancillary ligand, a chiral base, or a bimolecular mixture thereof. This study describes the development of new chiral bifunctional ligands based on a binaphthyl scaffold which incorporates both a phosphine and a carboxylic acid moiety. The optimal ligand provided high yields and enantioselectivities for a desymmetrizing C(sp2)?H arylation leading to 5,6‐dihydrophenanthridines, whereas the corresponding monofunctional ligands showed low enantioselectivities. The bifunctional system proved applicable to a range of substituted dihydrophenanthridines, and allowed the parallel kinetic resolution of racemic substrates. 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(16):4606-4610
An enantioselective PdII/Brønsted acid‐catalyzed carbonylative carbocyclization of enallenes ending with a cross‐dehydrogenative coupling (CDC) with a terminal alkyne was developed. VAPOL phosphoric acid was found as the best co‐catalyst among the examined 28 chiral acids, for inducing the enantioselectivity of α‐chiral ketones. As a result, a number of chiral cyclopentenones were easily synthesized in good to excellent enantiomeric ratio with good yields. 相似文献
7.
Stephanie Ganss Prof. Dr. Bernhard Breit 《Angewandte Chemie (International ed. in English)》2016,55(33):9738-9742
A highly attractive route toward macrolactones, which form the cyclic scaffold of a multitude of diverse natural compounds, is described. Although many chemical approaches to this structural motif have been explored, an asymmetric variant of the cyclization is unprecedented. Herein we present an enantioselective macrolactonization through an intramolecular atom‐economical rhodium‐catalyzed coupling of ω‐allenyl‐substituted carboxylic acids. The use of a modified diop ligand, chiral DTBM‐diop, led to high enantioselectivity (up to 93 % ee). The reaction tolerated a large variety of functionalities, including α,β‐unsaturated carboxylic acids and depsipeptides, and provided the desired macrocycles with very high enantio‐ and diastereoselectivity. 相似文献
8.
Isamu Shiina Kenya Nakata Keisuke Ono Teruaki Mukaiyama 《Helvetica chimica acta》2012,95(10):1891-1911
Pyridine‐3‐carboxylic anhydride (3‐PCA) was found to function as an efficient coupling reagent for the preparation of carboxylic esters from various carboxylic acids with alcohols under mild conditions by a simple experimental procedure. This novel condensation reagent 3‐PCA was applicable not only for the synthesis of achiral carboxylic esters catalyzed by 4‐(dimethylamino)pyridine (DMAP) but also for the production of chiral carboxylic esters by the combination of chiral nucleophilic catalyst, such as tetramisole (=2,3,5,6‐tetrahydro‐6‐phenylimidazo[2,1‐b][1,3]thiazole) derivatives. An efficient kinetic resolution of racemic benzylic alcohols with achiral carboxylic acids was achieved by using 3‐PCA in the presence of (R)‐benzotetramisole ((R)‐BTM), and a variety of optically active carboxylic esters were produced with high enantiomeric excesses by this new chiral induction system without using a tertiary amine. 相似文献
9.
Han Seul Park Zhoulong Fan Ru‐Yi Zhu Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(31):12853-12859
Reported herein is the distal γ‐C(sp3)?H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino‐acid directing group and using the ligand combination of a mono‐N‐protected amino acid (MPAA) and an electron‐deficient 2‐pyridone were critical for the γ‐C(sp3)?H olefination of ketone substrates. In addition, MPAAs enabled the γ‐C(sp3)?H olefination of free carboxylic acids to form diverse six‐membered lactones. Besides alkyl carboxylic acids, benzylic C(sp3)?H bonds also could be functionalized to form 3,4‐dihydroisocoumarin structures in a single step from 2‐methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ‐C(sp3)?H olefinated products. 相似文献
10.
《中国化学》2018,36(3):217-222
The first catalytic enantioselective C(sp)―C(sp3) cross‐coupling reaction between N‐tosylhydrazones and trialkylsilylethynes in the presence of Cu(I) salts and chiral phosphoramidite ligands was developed. A series of synthetically interesting, functionalized alkynes were obtained with moderate to good enantioselectivities (up to 83% ee). Cu(II) carbene migratory insertion is proposed to be the enantio‐determining step. 相似文献
11.
Palladium(II)‐Catalyzed Enantioselective Arylation of Unbiased Methylene C(sp3)−H Bonds Enabled by a 2‐Pyridinylisopropyl Auxiliary and Chiral Phosphoric Acids
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Sheng‐Yi Yan Ye‐Qiang Han Qi‐Jun Yao Xing‐Liang Nie Lei Liu Prof. Dr. Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2018,57(29):9093-9097
Enantioselective functionalizations of unbiased methylene C(sp3)?H bonds of linear systems by metal insertion are intrinsically challenging and remain a largely unsolved problem. Herein, we report a palladium(II)‐catalyzed enantioselective arylation of unbiased methylene β‐C(sp3)?H bonds enabled by the combination of a strongly coordinating bidentate PIP auxiliary with a monodentate chiral phosphoric acid (CPA). The synergistic effect between the PIP auxiliary and the non‐C2‐symmetric CPA is crucial for effective stereocontrol. A broad range of aliphatic carboxylic acids and aryl bromides can be used, providing β‐arylated aliphatic carboxylic acid derivatives in high yields (up to 96 %) with good enantioselectivities (up to 95:5 e.r.). Notably, this reaction also represents the first palladium(II)‐catalyzed enantioselective C?H activation with less reactive and cost‐effective aryl bromides as the arylating reagents. Mechanistic studies suggest that a single CPA is involved in the stereodetermining C?H palladation step. 相似文献
12.
Seiya Fukagawa Masahiro Kojima Tatsuhiko Yoshino Shigeki Matsunaga 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18322-18326
Catalytic enantioselective directed methylene C(sp3)?H amidation reactions of 8‐alkylquinolines using a Cp*RhIII/chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl‐based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C?H bonds, which leads to the formation of C?N bonds with good enantioselectivity. 相似文献
13.
Chiral Carboxylic Acid Enabled Achiral Rhodium(III)‐Catalyzed Enantioselective C−H Functionalization
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Dr. Luqing Lin Seiya Fukagawa Daichi Sekine Eiki Tomita Dr. Tatsuhiko Yoshino Prof. Dr. Shigeki Matsunaga 《Angewandte Chemie (International ed. in English)》2018,57(37):12048-12052
Reported is an achiral CpxRhIII/chiral carboxylic acid catalyzed asymmetric C?H alkylation of diarylmethanamines with a diazomalonate, followed by cyclization and decarboxylation to afford 1,4‐dihydroisoquinolin‐3(2H)‐one. Secondary alkylamines as well as nonprotected primary alkylamines underwent the transformation with high enantioselectivities (up to 98.5:1.5 e.r.) by using a newly developed chiral carboxylic acid as the sole source of chirality to achieve enantioselective C?H cleavage by a concerted metalation‐deprotonation mechanism. 相似文献
14.
Yan‐Shang Kang Ping Zhang Min‐Yan Li You‐Ke Chen Hua‐Jin Xu Jing Zhao Wei‐Yin Sun Jin‐Quan Yu Yi Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9197-9201
A ligand‐promoted RhIII‐catalyzed C(sp2)?H activation/thiolation of benzamides has been developed. Using bidentate mono‐N‐protected amino acid ligands led to the first example of RhIII‐catalyzed aryl thiolation reactions directed by weakly coordinating directing amide groups. The reaction tolerates a broad range of amides and disulfide reagents. 相似文献
15.
New mono boronic acid was found to be an enantioselective fluorescent chemosensor for mono alpha-hydroxyl carboxylic acids, such as mandelic acid and lactic acid. The chiral sensor shows lower background fluorescence, higher fluorescence enhancement, and enantioselective recognition kinetics toward mandelic acids and lactic acids. 相似文献
16.
Asymmetric Cascade Reaction to Allylic Sulfonamides from Allylic Alcohols by Palladium(II)/Base‐Catalyzed Rearrangement of Allylic Carbamates
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Dipl.‐Chem. Johannes Moritz Bauer Dr. Wolfgang Frey Prof. Dr. René Peters 《Angewandte Chemie (International ed. in English)》2014,53(29):7634-7638
A regio‐ and enantioselective tandem reaction is reported capable of directly transforming readily accessible achiral allylic alcohols into chiral sulfonyl‐protected allylic amines. The reaction is catalyzed by the cooperative action of a chiral ferrocene palladacycle and a tertiary amine base and combines high step‐economy with operational simplicity (e.g. no need for inert‐gas atmosphere or catalyst activation). Mechanistic studies support a PdII‐catalyzed [3,3] rearrangement of allylic carbamates—generated in situ from the allylic alcohol and an isocyanate—as the key step, which is followed by a decarboxylation. 相似文献
17.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(6):1528-1531
Herein we report acid‐directed β‐C(sp3)‐H arylation of α‐amino acids enabled by pyridine‐type ligands. This reaction does not require the installation of an exogenous directing group, is scalable, and enables the preparation of Fmoc‐protected unnatural amino acids in three steps. The pyridine‐type ligands are crucial for the development of this new C(sp3)‐H arylation. 相似文献
18.
Construction of Chiral Bridged Tricyclic Benzopyrans: Enantioselective Catalytic Diels–Alder Reaction and a One‐Pot Reduction/Acid‐Catalyzed Stereoselective Cyclization
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Aiguo Song Dr. Xishuai Zhang Xixi Song Xiaobei Chen Chenguang Yu He Huang Prof. Dr. Hao Li Prof. Dr. Wei Wang 《Angewandte Chemie (International ed. in English)》2014,53(19):4940-4944
An asymmetric two‐step approach to chiral bridged tricyclic benzopyrans, core structures featured in various natural products, is described. In the synthesis, an unprecedented enantioselective catalytic decarboxylative Diels–Alder reaction is developed using readily available coumarin‐3‐carboxylic acids and aldehydes as reactants under mild reaction conditions. Notably, the decarboxylation‐assisted release of the catalyst enables the process to proceed efficiently with high enantio‐ and diastereoselectivity. Furthermore, a one‐pot procedure for either a LiAlH4‐ or NaBH4‐mediated reduction with subsequent acid‐catalyzed intramolecular cyclization of the Diels–Alder adducts was identified for the efficient formation of the chiral bridged tricyclic benzopyrans. 相似文献
19.
Marnix Vangheluwe Thierry Verbiest Guy Koeckelberghs 《Journal of polymer science. Part A, Polymer chemistry》2008,46(14):4817-4829
New functionalized, (a)chiral poly(phenylene‐alt‐bithiophene)s were prepared and their chiroptical properties were studied. The polymers were prepared by a Stille coupling reaction and were functionalized with protected carboxylic acid and amino functions (tert‐butyl ester and BOC respectively). The polymers are present as well conjugated rigid rods in solution, which (chirally) aggregate in nonsolvents and film. In a next step, the protecting group (tert‐butyl ester in case of the carboxylic acid) was removed. Aggregation of this polymer can be induced by addition of amines; if chiral amines are used, the polymer chains chirally stack. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4817–4829, 2008 相似文献
20.
Yi‐Feng Wang Wei Zhang Shu‐Ping Luo Dr. Bai‐Lin Li Ai‐Bao Xia Ai‐Guo Zhong Dr. Dan‐Qian Xu Dr. 《化学:亚洲杂志》2009,4(12):1834-1838
Generally, amine‐catalyzed enantioselective transformations rely on chiral enamine or unsaturated iminium intermediates. Herein, we report a protocol involving dual activation by an aromatic iminium and hydrogen‐bonding. An enantioselective aza‐Michael–Henry domino reaction of 2‐aminobenzaldehydes with nitroolefins has been developed through this protocol using primary amine thiourea catalysts to provide a variety of 3‐nitro‐1,2‐dihydroquinolines in moderate yields and with up to 90 % ee. The mechanism for the catalytic enantioselective reaction was confirmed by ESI mass spectrometric detection of the reaction intermediates. The products formed are substructures found in skeletons of important biological and pharmaceutical molecules. 相似文献