共查询到20条相似文献,搜索用时 15 毫秒
1.
Qiong Tang Kai Fu Peiran Ruan Shunxi Dong Zhishan Su Xiaohua Liu Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11972-11977
A highly enantioselective formal conjugate allyl addition of allylboronic acids to β,γ‐unsaturated α‐ketoesters has been realized by employing a chiral NiII/N,N′‐dioxide complex as the catalyst. This transformation proceeds by an allylboration/oxy‐Cope rearrangement sequence, providing a facile and rapid route to γ‐allyl‐α‐ketoesters with moderate to good yields (65–92 %) and excellent ee values (90–99 % ee). The isolation of 1,2‐allylboration products provided insight into the mechanism of the subsequent oxy‐Cope rearrangement reaction: substrate‐induced chiral transfer and a chiral Lewis acid accelerated process. Based on the experimental investigations and DFT calculations, a rare boatlike transition‐state model is proposed as the origin of high chirality transfer during the oxy‐Cope rearrangement. 相似文献
2.
Maria Kitamura Prof. Yoshimi Hirokawa Prof. Dr. Naoyoshi Maezaki Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(38):9911-9917
We have accomplished highly enantioselective [2,3]‐Wittig rearrangements of functionalized allyl benzyl ethers in the presence of a chiral di‐tBu‐bis(oxazoline) ligand. In various oxygenated benzylic ethers, the reactions proceeded with excellent diastereo‐ and enantioselectivities, although the presence of a methoxy substituent at the ortho‐position on the benzyl group drastically decreased the enantioselectivity. Conversely, o‐ethyl and o‐phenyl substituents had no significant effect on the selectivity. We found that the C2‐substituent of the allylic moiety played an important role in producing high enantioselectivity. Highly enantioselective [2,3]‐Wittig rearrangement in the presence of catalytic amounts of the chiral ligands is also described. 相似文献
3.
Asymmetric Hetero‐Diels–Alder Reaction of Danishefsky’s Diene with α‐Ketoesters and Isatins Catalyzed by a Chiral N,N′‐Dioxide/Magnesium(II) Complex 下载免费PDF全文
Jianfeng Zheng Dr. Lili Lin Kai Fu Yulong Zhang Prof. Dr. Xiaohua Liu Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14493-14498
A highly enantioselective hetero‐Diels–Alder reaction of Danishefsky’s diene with α‐ketoesters and isatins has been realized by using a chiral N,N′‐dioxide/MgII complex. In the presence of only 0.1–0.5 mol % catalyst, a series of substrates were transformed into the corresponding tetrasubstituted 2,3‐dihydropyran‐4‐ones in up to 99 % yield and more than 99 % ee in two hours. 相似文献
4.
A series of chiral 1,3‐dioxolanes, 3 – 12 , with >99% ee values, have been synthesized. This is the first study of chiral ketalization reaction starting from ketones with aryl, monosubstituted aryl, and long alkyl chains (C11—AC13). Their ee values were determined by chiral high‐performance liquid chromatography (HPLC) on Chiralcel OD column, using their racemic 1,3‐dioxolanes rac‐ 3 – 12 , which were also synthesized for the first time. These chiral and racemic 1,3‐dioxolanes were characterizated by infrared, NMR (1H, 13C), mass spectrometry, elemental analysis, optical rotation, and chiral HPLC. 相似文献
5.
Xiaobin Lin Wei Yang Wenkun Yang Xiaohua Liu Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13626-13632
Catalytic enantioselective [2,3] Stevens and Sommelet–Hauser rearrangements of α‐diazo pyrazoleamides with sulfides were achieved by utilizing chiral N,N′‐dioxide/nickel(II) complex catalysts. These rearrangements proceeded well under mild reaction conditions, providing rapid and facile access to a series of functionalized 1,6‐dicarbonyls or sulfane‐substituted phenylacetates with high to excellent enantioselectivities. The catalytic system shows excellent stereocontrol, discriminating between the heterotopic lone pairs of sulfur and controlling both the 1,3‐proton transfer and the [2,3]‐σ rearrangement. 相似文献
6.
Asymmetric Ring Opening/Cyclization/Retro‐Mannich Reaction of Cyclopropyl Ketones with Aryl 1,2‐Diamines for the Synthesis of Benzimidazole Derivatives 下载免费PDF全文
Yong Xia Dr. Lili Lin Fenzhen Chang Yuting Liao Prof. Dr. Xiaohua Liu Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2016,55(40):12228-12232
A highly efficient asymmetric ring‐opening/cyclization/retro‐Mannich reaction of cyclopropyl ketones with aryl 1,2‐diamines has been realized using a chiral N,N′‐dioxide/ScIII catalyst. Benzimidazoles containing chiral side chains were generated under mild reaction conditions in excellent outcomes (up to 99 % yield and 97 % ee). This method also provides efficient access to chiral benzimidazole‐substituted amide and cycloheptene derivatives. 相似文献
7.
Shulin Ge Weidi Cao Tengfei Kang Bowen Hu Hang Zhang Zhishan Su Xiaohua Liu Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4057-4061
The enantioselective tandem reaction of β,γ‐unsaturated α‐ketoesters with β‐alkynyl ketones was realized by a bimetallic catalytic system of achiral AuΙΙΙ salt and chiral N,N′‐dioxide‐MgΙΙ complex. The cycloisomerization of β‐alkynyl ketone and asymmetric intermolecular [4+2] cycloaddition with β,γ‐unsaturated α‐ketoesters subsequently occurred, providing an efficient and straightforward access to chiral multifunctional 6,6‐spiroketals in up to 97 % yield, 94 % ee and >19/1 d.r. Besides, a catalytic cycle was proposed based on the results of control experiments. 相似文献
8.
Chiral N,N′‐Dioxide‐Organocatalyzed Regio‐, Diastereo‐ and Enantioselective Michael Addition–Alkylation Reaction 下载免费PDF全文
Juhua Feng Xiao Yuan Weiwei Luo Dr. Lili Lin Prof. Dr. Xiaohua Liu Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15650-15653
A highly regio‐, diastereo‐ and enantioselective Michael addition–alkylation reaction between α‐substituted cyano ketones and (Z)‐bromonitrostyrenes has been realized by using a chiral N,N′‐dioxide as organocatalyst. A variety of substrates performed well in this reaction, and the corresponding multifunctionalized chiral 2,3‐dihydrofurans were obtained in up to 95 % yield with 95:5 dr and 93 % ee. 相似文献
9.
An Efficient One‐pot Synthesis of Novel Spiro Cyclic 2‐Oxindole Derivatives of Pyrimido[4,5‐b]Quinoline,Pyrido[2,3‐d:6,5‐d′]Dipyrimidine and Indeno[2′,1′:5,6]Pyrido [2,3‐d]Pyrimidine in Water 下载免费PDF全文
Amr Mohamed Abdelmoniem Huwaida M. E. Hassaneen Ismail Abdelshafy Abdelhamid 《Journal of heterocyclic chemistry》2016,53(6):2084-2090
A novel and facile one‐pot synthesis of spiro cyclic 2‐oxindole derivatives of pyrimido[4,5‐b]quinoline‐4,6‐dione, pyrido[2,3‐d:6,5‐d′]dipyrimidine‐2,4,6‐trione, and indeno[2′,1′:5,6]pyrido [2,3‐d]pyrimidine employing 6‐aminothiouracil (or 6‐aminouracil), isatin, and cyclic 1,3‐diketone (e.g. 1,3‐indanedione, dimedone, or barbituric acid) has been developed. 相似文献
10.
Tatyana A. Stroganova Vladimir K. Vasilin Polina S. Shestakova Viktor M. Red'kin Gennady D. Krapivin 《Journal of heterocyclic chemistry》2015,52(1):227-234
3‐Acylaminofuro[2,3‐b]pyridine derivatives have been synthesized, and their behavior under acidic and basic conditions was studied. A new base‐catalyzed rearrangement of 3‐acylaminofuro[2,3‐b]pyridine derivatives into 3‐(oxazol‐4‐yl)pyridine‐2‐ones has been founded. 相似文献
11.
Lulu Wu Prof. Youming Wang Prof. Haibin Song Prof. Liangfu Tang Prof. Zhenghong Zhou Prof. Chuchi Tang 《化学:亚洲杂志》2013,8(9):2204-2210
An efficient procedure for the stereocontrolled construction of 2H‐thiopyrano[2,3‐b]quinoline scaffolds has been developed, starting from simple compounds. The domino Michael/aldol reactions between 2‐mercaptobenzaldehydes and enals, promoted by chiral diphenylprolinol TMS ether, proceed with excellent chemo‐ and enantioselectivity to give the corresponding synthetically useful and pharmaceutically valuable 2H‐thiopyrano[2,3‐b]quinolines in high yields with 90–99 % ee. 相似文献
12.
Cationic Ir/Me‐BIPAM‐Catalyzed Asymmetric Intramolecular Direct Hydroarylation of α‐Ketoamides 下载免费PDF全文
Tomohiko Shirai Prof. Dr. Hajime Ito Prof. Dr. Yasunori Yamamoto 《Angewandte Chemie (International ed. in English)》2014,53(10):2658-2661
Asymmetric intramolecular direct hydroarylation of α‐ketoamides gives various types of optically active 3‐substituted 3‐hydroxy‐2‐oxindoles in high yields with complete regioselectivity and high enantioselectivities (84–98 % ee). This is realized by the use of the cationic iridium complex [Ir(cod)2](BArF4) and the chiral O‐linked bidentate phosphoramidite (R,R)‐Me‐BIPAM. 相似文献
13.
Doyle J. Cassar Dr. Gennadiy Ilyashenko Dr. Muhammad Ismail James Woods Dr. David L. Hughes Dr. Christopher J. Richards 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(52):17951-17962
The reaction of (η5‐(N,N‐dimethylaminomethyl)cyclopentadien‐yl)(η4‐tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)‐N‐acetylphenylalanine gave planar chiral palladacycle di‐μ‐chloridebis[(η5‐(Sp)‐2‐(N,N‐dimethylaminomethyl)cyclopentadienyl,1‐C,3′‐N)(η4‐tetraphenylcyclobutadiene)cobalt]dipalladium [(Sp)‐Me2‐CAP‐Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)‐proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (Sp)‐Me2‐CAP‐OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)‐N‐acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N‐diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(Sp)‐Pyrr‐CAP‐Cl] and AgNO3 (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)‐N‐aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)‐trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non‐racemic allylic amine derivatives. 相似文献
14.
Enantioselective Construction of 2,3‐Dihydrofuro[2,3‐b]quinolines through Supramolecular Hydrogen Bonding Interactions 下载免费PDF全文
Dr. Fangrui Zhong Prof. Dr. Thorsten Bach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13522-13526
The first asymmetric synthesis of 2,3‐dihydrofuro[2,3‐b]quinolines has been achieved by a cascade asymmetric aziridination/intramolecular ring‐opening process of differently substituted 3‐alkenylquinolones. Good yields and high enantioselectivities (up to 78 % yield and 95 % ee) were recorded when employing 2,2,2‐trichloroethoxysulfonamide as the nitrene source, PhI(OCOtBu)2 as the oxidant, and a chiral C2‐symmetric RhII complex as the catalyst (1 mol %). The catalyst bears two lactam motifs, which serve as binding sites for substrate coordination through supramolecular hydrogen‐bonding interactions. 相似文献
15.
Asymmetric Hydroalkoxylation of Non‐Activated Alkenes: Titanium‐Catalyzed Cycloisomerization of Allylphenols at High Temperatures 下载免费PDF全文
M. Sc. Johannes Schlüter M. Sc. Max Blazejak Dr. Florian Boeck Prof. Dr. Lukas Hintermann 《Angewandte Chemie (International ed. in English)》2015,54(13):4014-4017
The asymmetric catalytic addition of alcohols (phenols) to non‐activated alkenes has been realized through the cycloisomerization of 2‐allylphenols to 2‐methyl‐2,3‐dihydrobenzofurans (2‐methylcoumarans). The reaction was catalyzed by a chiral titanium–carboxylate complex at uncommonly high temperatures for asymmetric catalytic reactions. The catalyst was generated by mixing titanium isopropoxide, the chiral ligand (aS)‐1‐(2‐methoxy‐1‐naphthyl)‐2‐naphthoic acid or its derivatives, and a co‐catalytic amount of water in a ratio of 1:1:1 (5 mol % each). This homogeneous thermal catalysis (HOT‐CAT) gave various (S)‐2‐methylcoumarans with yields of up to 90 % and in up to 85 % ee at 240 °C, and in 87 % ee at 220 °C. 相似文献
16.
Direct Synthesis of Benzofuro[2,3‐b]pyrroles through a Radical Addition/[3,3]‐Sigmatropic Rearrangement/Cyclization/Lactamization Cascade 下载免费PDF全文
Dr. Masafumi Ueda Yuta Ito Yuki Ichii Maiko Kakiuchi Hiroko Shono Prof. Dr. Okiko Miyata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6763-6770
A straightforward synthetic method for the construction of benzofuro[2,3‐b]pyrrol‐2‐ones by a novel domino reaction through a radical addition/[3,3]‐sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O‐phenyl‐conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C?C bonds, a C?O bond, and a C?N bond in a single operation, leading to pyrrolidine‐fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3‐b]pyrrol‐2‐one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed. 相似文献
17.
Asymmetric Conjugate Alkynylation of Cyclic α,β‐Unsaturated Carbonyl Compounds with a Chiral Diene Rhodium Catalyst 下载免费PDF全文
Dr. Xiaowei Dou Dr. Yinhua Huang Prof. Dr. Tamio Hayashi 《Angewandte Chemie (International ed. in English)》2016,55(3):1133-1137
Asymmetric conjugate alkynylation of cyclic α,β‐unsaturated carbonyl compounds (ketones, esters, and amides) was realized by use of diphenyl[(triisopropylsilyl)ethynyl]methanol as an alkynylating reagent in the presence of a rhodium catalyst coordinated with a new chiral diene ligand (Fc‐bod; bod=bicyclo[2.2.2]octa‐2,5‐diene, Fc=ferrocenyl) to give high yields of the corresponding β‐alkynyl‐substituted carbonyl compounds with 95–98 % ee. 相似文献
18.
Desilylation‐Activated Propargylic Transformation: Enantioselective Copper‐Catalyzed [3+2] Cycloaddition of Propargylic Esters with β‐Naphthol or Phenol Derivatives 下载免费PDF全文
Long Shao Ya‐Hui Wang De‐Yang Zhang Prof. Dr. Jie Xu Prof. Dr. Xiang‐Ping Hu 《Angewandte Chemie (International ed. in English)》2016,55(16):5014-5018
A copper‐catalyzed asymmetric [3+2] cycloaddition of 3‐trimethylsilylpropargylic esters with either β‐naphthols or electron‐rich phenols has been realized and proceeds by a desilylation‐activated process. Under the catalysis of Cu(OAc)2?H2O in combination with a structurally optimized ketimine P,N,N‐ligand, a wide range of optically active 1,2‐dihydronaphtho[2,1‐b]furans or 2,3‐dihydrobenzofurans were obtained in good yields and with high enantioselectivities (up to 96 % ee). This represents the first desilylation‐activated catalytic asymmetric propargylic transformation. 相似文献
19.
Abdul Motaleb Soniya Rani Tamal Das Rajesh G. Gonnade Pradip Maity 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14242-14247
A phosphite‐mediated [2,3]‐aza‐Wittig rearrangement has been developed for the regio‐ and enantioselective allylic alkylation of six‐membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N‐allyl salts undergo a stereoselective base‐mediated aza‐Wittig rearrangement and dissociation of the chiral phosphite for overall C?H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities. 相似文献
20.
Highly Enantioselective Carbonyl–Ene Reactions of 2,3‐Diketoesters: Efficient and Atom‐Economical Process to Functionalized Chiral α‐Hydroxy‐β‐Ketoesters 下载免费PDF全文
Phong M. Truong Dr. Peter Y. Zavalij Prof. Michael P. Doyle 《Angewandte Chemie (International ed. in English)》2014,53(25):6468-6472
Carbonyl–ene reactions of 2,3‐diketoesters catalyzed by [Cu{(S,S)‐tBu‐box}](SbF6)2 [box=bis(oxazoline)] generate chiral α‐functionalized α‐hydroxy‐β‐ketoesters in up to 94 % yield and 97 % ee. The 2,3‐diketoesters are conveniently accessed from the corresponding α‐diazo‐β‐ketoester, and a catalyst loading as low as 1.0 mol % can be achieved. 相似文献