共查询到20条相似文献,搜索用时 31 毫秒
1.
Linqing Wang Dan Li Dongxu Yang Kezhou Wang Jie Wang Pengxin Wang Prof. Dr. Wu Su Prof. Dr. Rui Wang 《化学:亚洲杂志》2016,11(5):691-695
A highly enantioselective ring‐opening alkylation reaction between 3‐aryl‐oxindole and N‐(2‐picolinoyl) aziridine has been realized for the first time. The reaction is efficiently mediated by a simple in‐situ‐generated magnesium catalyst and 3,3′‐fluorinated‐BINOL (BINOL=1,1′‐binaphthalene‐2,2′‐diol) has been identified as a powerful chiral ligand. Notably, the fluorine atom on the chiral ligand plays a key role in providing the desired chiral 3‐alkyl‐3‐aryl oxindoles with excellent enantioselectivities. 相似文献
2.
Catalytic Asymmetric Intramolecular Homologation of Ketones with α‐Diazoesters: Synthesis of Cyclic α‐Aryl/Alkyl β‐Ketoesters
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Wei Li Fei Tan Xiaoyu Hao Gang Wang Yu Tang Prof. Dr. Xiaohua Liu Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2015,54(5):1608-1611
A catalytic asymmetric intramolecular homologation of simple ketones with α‐diazoesters was firstly accomplished with a chiral N,N′‐dioxide–Sc(OTf)3 complex. This method provides an efficient access to chiral cyclic α‐aryl/alkyl β‐ketoesters containing an all‐carbon quaternary stereocenter. Under mild conditions, a variety of aryl‐ and alkyl‐substituted ketone groups reacted with α‐diazoester groups smoothly through an intramolecular addition/rearrangement process, producing the β‐ketoesters in high yield and enantiomeric excess. 相似文献
3.
Paola Peluso Victor Mamane Emmanuel Aubert Sergio Cossu 《Journal of separation science》2013,36(18):2993-3003
The HPLC enantioseparation of nine atropisomeric 3,3′,5,5′‐tetrasubstituted‐4,4′‐bipyridines was performed in normal and polar organic (PO) phase modes using two immobilized polysaccharide‐based chiral columns, namely, Chiralpak IA and Chiralpak IC. The separation of all racemic analytes, the effect of the chiral selector, and mobile phase (MP) composition on enantioseparation and the enantiomer elution order (EEO) were studied. The beneficial effect of nonstandard solvents, such as tetrahydrofuran (THF), dichloromethane (DCM), and methyl t‐butyl ether on enantioseparation was investigated. All selected 4,4′‐bipyridines were successfully enantioseparated on Chiralpak IA under normal or PO MPs with separation factors from 1.14 to 1.70 and resolutions from 1.3 to 6.5. Two bipyridines were enantioseparated at the multimilligram level on Chiralpak IA. Differently, Chiralpak IC was less versatile toward the considered class of compounds and only five bipyridines out of nine could be efficiently separated. In particular, on these columns, the ternary mixture n‐heptane/THF/DCM (90:5:5) as MP had a positive effect on enantioseparation. An interesting phenomenon of reversal of the EEO depending on the composition of the MP for the 3,3′‐dibromo‐5,5′‐bis‐(E)‐phenylethenyl‐4,4′‐bipyridine along with an exceptional enantioseparation for the 3,3′‐dibromo‐5,5′‐bis‐ferrocenylethynyl‐4,4′‐bipyridine (α = 8.33, Rs = 30.6) were observed on Chiralpak IC. 相似文献
4.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(12):1282-1288
Two kinds of chiral 1,1′‐binaphthol (BINOL)‐based polymer enantiomers were designed and synthesized by the polymerization of 5,5′‐((2,2′‐bis (octyloxy)‐[1,1′‐binaphthalene]‐3,3′‐diyl)bis(ethyne‐2,1‐diyl))bis(2‐hydroxybenzaldehyde) ( M1 ) with alkyl diamine ( M2 ) via nucleophilic addition–elimination reaction. The resulting chiral polymers can exhibit mirror image cotton effects either in the absence or in the presence of Zn2+ ion. Almost no fluorescence or circularly polarized luminescence (CPL) emission could be observed for two chiral BINOL‐based polymer enantiomers in the absence of Zn2+. Interestingly, the chiral polymers can show strong fluorescence and CPL response signals upon the addition of Zn2+, which can be attributed to Zn2+‐coordination fluorescence enhancement effect. This work can develop a new strategy on the design of the novel CPL materials via metal‐coordination reaction. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1282–1288 相似文献
5.
Chun Ma Fei Jiang Feng‐Tao Sheng Yinchun Jiao Guang‐Jian Mei Feng Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3046-3052
The first catalytic asymmetric construction of 3,3′‐bisindole skeletons bearing both axial and central chirality has been established by organocatalytic asymmetric addition reactions of 2‐substituted 3,3′‐bisindoles with 3‐indolylmethanols (up to 98 % yield, all >95:5 d.r., >99 % ee). This reaction also represents the first highly enantioselective construction of axially chiral 3,3′‐bisindole skeletons, and utilizes the strategy of introducing a bulky group to the ortho‐position of prochiral 3,3′‐bisindoles. This reaction not only provides a good example for simultaneously controlling axial and central chirality in one operation, but also serves as a new strategy for catalytic enantioselective construction of axially chiral 3,3′‐bisindole backbones from prochiral substrates. 相似文献
6.
Hui Yang Wen‐Hua Zheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16323-16326
A highly efficient kinetic resolution of racemic amino alcohols has been achieved for the first time with a chiral tin catalyst. A chiral organotin compound with 3,4,5‐trifluorophenyl groups at the 3,3′‐positions of the binaphthyl framework enabled this transformation with excellent yield and high enantioselectivity. The process tolerates aryl‐ and alkyl‐substituted amino alcohols and a variety of other substrates, affording the corresponding products in high enantioselectivity and with s factors up to >500. 相似文献
7.
An Imidazoline–Aminophenol (IAP) Nickel Catalyst: Structure and Catalytic Activity in the Enantioselective 1,4‐Addition of 3′‐Indolyl‐3‐Oxindoles to Nitroethylene
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Atsuko Awata Makiko Wasai Prof. Dr. Hyuma Masu Sayaka Kado Prof. Dr. Takayoshi Arai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2470-2477
The structure of a nickel complex of imidazoline–aminophenol (IAP) prepared from IAP with Ni(OAc)2 was elucidated as cis‐bis(imidazolineaminophenoxide) [Ni(IAP)2]. The [Ni(IAP)2] complex smoothly promoted catalytic asymmetric 1,4‐addition of 3′‐indolyl‐3‐oxindole to nitroethylene to provide chiral mixed 3,3′‐bisindoles with high enantioselectivities. Mechanistic studies using ESI‐MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)2] to generate the Ni–enolate of 3′‐indolyl‐3‐oxindole. From the optically active 3,3′‐mixed indole adduct, biologically important 3′‐indolyl‐3‐pyrrolidinoindoline was successfully synthesized in a three‐step reaction sequence. 相似文献
8.
Yu‐Hua Liao Xiong‐Li Liu Dr. Zhi‐Jun Wu Prof. Xi‐Lin Du Prof. Dr. Xiao‐Mei Zhang Prof. Dr. Wei‐Cheng Yuan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(21):6679-6687
An asymmetric conjugate addition of 3‐monosubstituted oxindoles to a range of (E)‐1,4‐diaryl‐2‐buten‐1,4‐diones, catalyzed by commercially available cinchonine, is described. This organocatalytic asymmetric reaction affords a broad range of 3,3′‐disubstituted oxindoles that contain a 1,4‐dicarbonyl moiety and vicinal quaternary and tertiary stereogenic centers in high‐to‐excellent yields (up to 98 %), with excellent diastereomeric and moderate‐to‐high enantiomeric ratios (up to 99:1 and 95:5, respectively). Subsequently, cyclization of the 1,4‐dicarbonyl moiety in the resultant Michael adducts under different Paal–Knorr conditions results in two new kinds of 3,3′‐disubstituted oxindoles—3‐furanyl‐ and 3‐pyrrolyl‐3‐alkyl‐oxindoles—in high yields and good enantioselectivities. Notably, the studies presented here sufficiently confirm that this two‐step strategy of sequential conjugate addition/Paal–Knorr cyclization is not only an attractive method for the indirect enantioselective heteroarylation of 3‐alkyloxindoles, but also opens up new avenues toward asymmetric synthesis of structurally diverse 3,3′‐disubstituted oxindole derivatives. 相似文献
9.
Hee Jung Choi Hwan Sun Cho Sang Cheol Han Myung Ho Hyun 《Journal of separation science》2009,32(4):536-541
A residual silanol group‐protecting chiral stationary phase (CSP) based on optically active (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6 was successfully applied to the resolution of fluoroquinolone compounds including gemifloxacin mesylate. The chiral recognition ability of the residual silanol group‐protecting CSP was generally greater than that of the residual silanol group‐containing CSP. From these results, it was concluded that the simple protection of the residual silanol groups of the latter CSP with lipophilic n‐octyl groups can improve its chiral recognition ability for the resolution of racemic fluoroquinolone compounds. The chromatographic resolution behaviors were investigated as a function of the content and type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature. Especially, the addition of ammonium acetate to the mobile phase was found to be a quite effective means of reducing the enantiomer retentions without sacrificing the chiral recognition efficiency of the CSP. 相似文献
10.
Oxidative Asymmetric Aza‐Friedel–Crafts Alkylation of Indoles with 3‐Indolinone‐2‐carboxylates Catalyzed by a BINOL Phosphoric Acid and Promoted by DDQ
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An asymmetric aza‐Friedel–Crafts alkylation reaction between indoles and indolenines that were derived in situ from 3‐indolinone‐2‐carboxylates has been developed by using 3,3′‐bis(triphenylsilyl)‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate as a catalyst. The reaction proceeded under mild conditions and provided chiral indol‐3‐yl‐3‐indolinone‐2‐carboxylate derivatives in good yields with excellent ee values (up to 98.6 %). Similarly, the Mannich‐type addition of indoline‐3‐ones to indolenines provided heterodimers with vicinal chiral quaternary centers. This method was successfully applied to the construction of the core structure of trigonoliimine C. 相似文献
11.
Wenbo Li Yuying Li Dr. Guanghua Zhou Xiangshu Wu Prof. Dr. Junliang Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(47):15113-15121
A series of 2‐alkynyl carbonyl compounds that contain a cyclopentene ring or a heterocycle can be transformed into various fused dihydrobenzofurans and tetrahydrofuro[2,3‐c]pyridines by means of a 1,2‐alkyl migration process. Both of these reactions proceed with excellent regioselectivity and stereospecificity when using a cationic gold(I) catalyst. Treatment of 4‐styrylcyclopent‐1‐enecarboxylates under different conditions affords a range of highly functionalized dihydrobenzofurans and dihydroisobenzofurans. A divergence in product selectivity, which depends on the anion of the silver salts used, was observed. Interestingly, ring‐fused tetrahydroquinolines undergo only 1,2′‐alkyl migration reaction by means of a C? C cleavage/cyclization sequence to provide tetrahydroazepine derivatives. Mechanistic studies suggest that the gold complexes catalyze 1,2‐alkyl migration reactions through a concerted reaction pathway and 1,2′‐alkyl migration reactions through a stepwise reaction pathway. 相似文献
12.
A facile route for the synthesis of 2‐substituted biquinazolinones incorporating a chiral center into one of their lateral appendage, via condensation of 4H‐3,1‐benzoxazin‐4‐one with 3‐amino‐2S‐substituted‐quinazolin‐4‐ones, is described. The methodology is straightforward and does not require chromatographic purification at any stage. The products are obtained in good yields as mixture of diastereoisomers, which can be enriched with the major diastereoisomer by simple recrystallization. The functional groups in the lateral chain can be easily modified allowing the synthesis of a variety of 3,3′‐biquinazoline‐4,4′‐diones. The synthesis of symmetrically 2,2′ chirally disubstituted biquinazolinones via acylation/dehydration sequence of bisanthraniloyl hydrazine is also described. 相似文献
13.
Long Yin Junhao Xing Yuhan Wang Yue Shen Tao Lu Tamio Hayashi Xiaowei Dou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2496-2500
The enantioselective synthesis of a series of C2‐symmetric 3,3′‐diarylated 1,1′‐spirobiindane‐7,7′‐diols (3,3′‐diaryl‐SPINOLs) was developed by sequential Rh‐catalyzed twofold asymmetric conjugate arylation/BF3‐promoted diastereoselective spirocyclization (>20:1 d.r. and >99 % ee for all examples). Some phosphoramidite ligands were prepared from the 3,3′‐Ph‐SPINOL and applied to several catalytic asymmetric reactions, and the 3,3′‐diarylated ligands showed higher enantioselectivities than the privileged nonsubstituted ligands. 相似文献
14.
Alkylation of ambident thymidine 5′‐O‐(O‐alkyl phosphorothioate) anions by means of 3′‐O‐sulfonylated xylothymidine occurs at both O‐ and S‐nucleophilic centers, and formation of an internucleotide bond is accompanied by the process of elimination. Lack of chemoselectivity and low yields of products discriminate against such an approach as an effective method of stereocontrolled synthesis of P‐chiral oligo(nucleoside phosphorothioate)s. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 91–104, 1999 相似文献
15.
Highly Enantioselective Aza‐Michael Reaction between Alkyl Amines and β‐Trifluoromethyl β‐Aryl Nitroolefins
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Dr. Yong Huang 《Angewandte Chemie (International ed. in English)》2015,54(51):15414-15418
The aza‐Michael addition reaction is a vital transformation for the synthesis of functionalized chiral amines. Despite intensive research, enantioselective aza‐Michael reactions with alkyl amines as the nitrogen donor have not been successful. We report the use of chiral N‐heterocyclic carbenes (NHCs) as noncovalent organocatalysts to promote a highly selective aza‐Michael reaction between primary alkyl amines and β‐trifluoromethyl β‐aryl nitroolefins. In contrast to classical conjugate‐addition reactions, a strategy of HOMO‐raising activation was used. Chiral trifluoromethylated amines were synthesized in high yield (up to 99 %) with excellent enantioselectivity (up to 98 % ee). 相似文献
16.
Organocatalytic Highly Enantioselective Substitution of 3‐(1‐Tosylalkyl)indoles with Oxindoles Enables the First Total Synthesis of (+)‐Trigolutes B
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jian‐Zhou Huang Chen‐Long Zhang Yi‐Fan Zhu Lu‐Lu Li Dian‐Feng Chen Zhi‐Yong Han Prof. Dr. Liu‐Zhu Gong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8389-8393
A highly enantioselective organocatalytic substitution of 3‐(1‐tosylalkyl)indoles with oxindoles has been established by using chiral bifunctional organocatalysts, providing an efficient entry to multiply functionalized 3,3′‐disubstituted oxindoles, and was exploited as the key step to enable the first asymmetric total synthesis of optically pure (+)‐trigolutes B to be accomplished in a concise manner, within seven steps with an 18 % overall yield. 相似文献
17.
A series of oligonucleotides containing (5′S)‐5′‐C‐butyl‐ and (5′S)‐5′‐C‐isopentyl‐substituted 2′‐deoxyribonucleosides were designed, prepared, and characterized with the intention to explore alkyl‐zipper formation between opposing alkyl chains across the minor groove of oligonucleotide duplexes as a means to modulate DNA‐duplex stability. From four possible arrangements of the alkyl groups that differ in the density of packing of the alkyl chains across the minor groove, three (duplex types I – III , Fig. 2) could experimentally be realized and their duplex‐forming properties analyzed by UV‐melting curves, CD spectroscopy, and isothermal titration calorimetry (ITC), as well as by molecular modeling. The results show that all arrangements of alkyl residues within the minor groove of DNA are thermally destabilizing by 1.5–3°/modification in Tm. We found that, within the proposed duplexes with more loosely packed alkyl groups (type‐ III duplexes), accommodation of alkyl residues without extended distorsion of the helical parameters of B‐DNA is possible but does not lead to higher thermodynamic stability. The more densely packed and more unevenly distributed arrangement (type‐ II duplexes) seems to suffer from ecliptic positioning of opposite alkyl groups, which might account for a systematic negative contribution to stability due to steric interactions. The decreased stability in the type‐ III duplexes described here may be due either to missing hydrophobic interactions of the alkyl groups (not bulky enough to make close contacts), or to an overcompensation of favorable alkyl‐zipper formation presumably by loss of structured H2O in the minor groove. 相似文献
18.
Maria Gabriella Vigorita Rosaria Ottan Francesca Monforte Tindara Previtera Rosanna Maccari 《Journal of heterocyclic chemistry》2001,38(2):485-489
Diastereomers of antiinflammatory/analgesic and antihistaminic 3,3′[(1,2‐ethanediyl)bis(2‐aryl‐4‐thiazo‐lidinone)] derivatives possessing two stereogenic centers (indicated as BIS 2*C) have been widely investigated in recent years. The 5,5′‐dimethyl analogues (BIS 4*C), now reported, have been synthesized by reaction of (±) α‐mercaptopropionic acid and N,N'‐di(3‐fluorobenzyliden)ethylenediamine. Because the 2 and 2′carbons bear the same groups and similarly the 5 and 5′ carbons, and the latter groups are different from the former, four enantiomeric pairs and two meso forms exist in this situation. These diastereomers were identified by the concerted use of nmr spectroscopy and hplc on chiral stationary phase. 相似文献
19.
Clemens K. Blasius Niklas F. Heinrich Vladislav Vasilenko Lutz H. Gade 《Angewandte Chemie (International ed. in English)》2020,59(37):15974-15977
A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N‐alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N‐alkyl imines provided the corresponding α‐chiral amines in excellent yields and with up to >99 % ee. The applicability of this base metal catalytic system was further demonstrated with the synthesis of the pharmaceuticals Fendiline and Tecalcet. 相似文献
20.
Marcos A. Kettner Prof. Dr. Konstantin Karaghiosoff Prof. Dr. Thomas M. Klapötke Dr. Muhamed Sućeska Swetlana Wunder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7622-7631
Here we report on the preparation of two hydrogen atom free 3,3′‐bi(1,2,4‐oxadiazole) derivatives. 5,5′‐Bis(fluorodinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole) was synthesised by fluorination of diammonium 5,5′‐bis(dinitromethanide)‐3,3′‐bi(1,2,4‐oxadiazole). For our previously reported analogue 5,5′‐bis(trinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole), a new synthetic route starting from new 3,3′‐bi(1,2,4‐oxadiazolyl)‐5,5′‐diacetic acid was developed. In this course also hitherto unknown 5,5′‐dimethyl‐3,3′‐bi(1,2,4‐oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X‐ray diffraction studies were performed and the crystal structures for the 5,5'‐dimethyl and 5,5'‐(fluorodinitromethyl) derivatives are reported. The energetic 5,5'‐(fluorodinitromethyl) and 5,5'‐(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS‐4M enthalpies. With these values and the room‐temperature X‐ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code. 相似文献