共查询到20条相似文献,搜索用时 31 毫秒
1.
Catalytic Asymmetric Formal [3+3] Cycloaddition of an Azomethine Ylide with 3‐Indolylmethanol: Enantioselective Construction of a Six‐Membered Piperidine Framework
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)
Prof. Dr. Feng Shi Ren‐Yi Zhu Wei Dai Cong‐Shuai Wang Prof. Shu‐Jiang Tu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2597-2604
A catalytic asymmetric formal [3+3] cycloaddition of 3‐indolylmethanol and an in situ‐generated azomethine ylide has been established to construct a chiral six‐membered piperidine framework with two stereogenic centers. This approach not only represents the first enantioselective cycloaddition of isatin‐derived 3‐indolylmethanol, but also has realized an unusual enantioselective formal [3+3] cycloaddition of azomethine ylide rather than its common [3+2] cycloadditions. Besides, this protocol combines the merits of a multicomponent reaction and organocatalysis, which efficiently assembles a variety of isatin‐derived 3‐indolylmethanols, aldehydes, and amino esters into structurally diverse spiro[indoline‐3,4′‐pyridoindoles] with one all‐carbon quaternary stereogenic center in high yields and excellent enantioselectivities (up to 93 % yield, >99 % enantiomeric excess (ee)). Although the diastereoselectivity of the reaction is generally moderate, most of the diastereomers can be separated by using column chromatography followed by preparative TLC. 相似文献
2.
Enantioselective Formal [4+2] Cycloadditions to 3‐Nitroindoles by Trienamine Catalysis: Synthesis of Chiral Dihydrocarbazoles
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)
Yang Li Dr. Fernando Tur Rune Pagh Nielsen Dr. Hao Jiang Prof. Dr. Frank Jensen Prof. Dr. Karl Anker Jørgensen 《Angewandte Chemie (International ed. in English)》2016,55(3):1020-1024
The first enantioselective formal [4+2] cycloadditions of 3‐nitroindoles are presented. By using 3‐nitroindoles in combination with an organocatalyst, chiral dihydrocarbazole scaffolds are formed in moderate to good yields (up to 87 %) and enantioselectivities (up to 97 % ee). The reaction was extended to include enantioselective [4+2] cycloadditions of 3‐nitrobenzothiophene. The reaction proceeds through a [4+2] cycloaddition/elimination cascade under mild reaction conditions. Furthermore, a diastereoselective reduction of an enantioenriched cycloadduct is presented. The mechanism of the reaction is discussed based on experimental and computational studies. 相似文献
3.
PyBidine/Copper Catalyst: Asymmetric exo′‐Selective [3+2] Cycloaddition using Imino Ester and Electrophilic Indole
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. Atsuko Awata Prof. Dr. Takayoshi Arai 《Angewandte Chemie (International ed. in English)》2014,53(39):10462-10465
Electrophilic indoles having two electron‐withdrawing groups undergo nucleophilic attack at C2 and electrophilic functionalization at C3. This is the first enantioselective formal [3+2] cycloaddition using electrophilic indoles. The PyBidine/Cu catalyst smoothly promoted highly enantio‐ and exo′‐selective [3+2] cycloaddition using imino esters and 3‐nitroindoles. This reaction provides a method for the preparation of diverse and complex chiral pyrroloindoline compounds. 相似文献
4.
Asymmetric Brønsted Base Catalyzed and Directed [3+2] Cycloaddition of 2‐Acyl Cycloheptatrienes with Azomethine Ylides
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)
Vibeke H. Lauridsen Lise Ibsen Jakob Blom Prof. Dr. Karl Anker Jørgensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3259-3263
Conjugated cyclic trienes have the potential for different types of cycloaddition reactions. In the present work, we will, in a novel asymmetric cycloaddition reaction, demonstrate that the organocatalytic reaction of 2‐acyl cycloheptatrienes with azomethine ylides proceeds as a [3+2] cycloaddition, which is in contrast to the Lewis acid‐catalyzed reaction, in which a [3+6] cycloaddition takes place. In the presence of a chiral organosuperbase, 2‐acyl cycloheptatrienes react in a highly enantioselective manner in the [3+2] cycloaddition with azomethine ylides, providing the 1,3‐dipolar cycloaddition product in high yields and up to 99 % ee. It is also shown that the diene formed by the reaction can undergo stereoselective dihydroxylation, bromination, and cycloaddition reactions. Finally, based on experimental observations, some mechanistic considerations are discussed. 相似文献
5.
Asymmetric Isothiourea‐Catalysed Formal [3+2] Cycloadditions of Ammonium Enolates with Oxaziridines
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)
Siobhan R. Smith Dr. Charlene Fallan Dr. James E. Taylor Ross McLennan Dr. David S. B. Daniels Dr. Louis C. Morrill Prof. Alexandra M. Z. Slawin Prof. Andrew D. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10530-10536
A highly enantioselective Lewis base‐catalysed formal [3+2] cycloaddition of ammonium enolates and oxaziridines to give stereodefined oxazolidin‐4‐ones in high yield is described. Employing an enantioenriched oxaziridine in this process leads to a matched/mis‐matched effect with the isothiourea catalyst and allowed the synthesis of either syn‐ or anti‐stereodefined oxazolidin‐4‐ones in high d.r., yield and ee. Additionally, the oxazolidin‐4‐one products have been derivatised to afford functionalised enantioenriched building blocks. 相似文献
6.
Rhodium‐Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides
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)
Tomoka Yoshida Yuki Tajima Masayuki Kobayashi Koji Masutomi Prof. Dr. Keiichi Noguchi Prof. Dr. Ken Tanaka 《Angewandte Chemie (International ed. in English)》2015,54(28):8241-8244
It has been established that a cationic rhodium(I)/H8‐binap complex catalyzes the [3+2+2] cycloaddition of 1,6‐diynes with cyclopropylideneacetamides to produce cycloheptadiene derivatives through cleavage of cyclopropane rings. In contrast, a cationic rhodium(I)/(S)‐binap complex catalyzes the enantioselective [2+2+2] cycloaddition of terminal alkynes, acetylenedicarboxylates, and cyclopropylideneacetamides to produce spiro‐cyclohexadiene derivatives which retain the cyclopropane rings. 相似文献
7.
A Chiral N,N′‐Dioxide–ZnII Complex Catalyzes the Enantioselective [2+2] Cycloaddition of Alkynones with Cyclic Enol Silyl Ethers
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)
Tengfei Kang Shulin Ge Dr. Lili Lin Yan Lu Prof. Dr. Xiaohua Liu Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2016,55(18):5541-5544
A highly efficient enantioselective [2+2] cycloaddition between alkynones and cyclic enol silyl ethers was developed by using a chiral N,N′‐dioxide‐zinc(II) complex as a catalyst. This method functions well for a variety of terminal alkynes as well as cyclic enol silyl ethers, with good to excellent enantioselectivity (up to 97 % ee). This is also the first successful example for the catalytic enantioselective [2+2] cycloaddition of internal alkynes with cyclic enol silyl ethers to give fully substituted cyclobutenes. Meanwhile, the desired cyclobutene product can easily be transformed into fused cyclobutane derivatives. 相似文献
8.
Enantioselective and Regiodivergent Functionalization of N‐Allylcarbamates by Mechanistically Divergent Multicatalysis
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)
Dr. Edward Richmond Ismat Ullah Khan Dr. Joseph Moran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12274-12277
A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel‐catalyzed isomerization of N‐allylcarbamates and subsequent phosphoric‐acid‐catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene‐carbamates are mechanistically partitioned to yield opposing functionalized products. Formal α‐functionalization to give protected α‐arylamines is achieved upon enantioselective Friedel–Crafts reaction with arene nucleophiles, whereas formal β‐functionalization is achieved upon reaction with diarylimine electrophiles in an enantioselective Povarov‐[4+2] cycloaddition. 相似文献
9.
An efficient enantioselective synthesis of 3‐acetoxy trans‐β‐lactams 7a and 7b via [2+2] cycloaddition reactions of imines 4a and 4b , derived from a polycyclic aromatic amine and bicyclic chiral acid obtained from (+)‐car‐3‐ene, is described. The cycloaddition was found to be highly enantioselective, producing only trans‐(3R,4R)‐N‐azetidin‐2‐one in very good yields. This is the first report of the synthesis of enantiomerically pure trans‐β‐lactams 7a and 7b with a polycyclic aromatic substituent at N(1) of the azetidin ring. 相似文献
10.
Yun‐Zhou Zhao Hai‐Bin Yang Prof. Dr. Xiang‐Ying Tang Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3562-3566
RhII‐catalyzed intermolecular [3+2] cycloaddition of 2 H‐azirines with N‐sulfonyl‐1,2,3‐triazoles is disclosed, in which a series of fully functionalized pyrroles is produced via rhodium azavinyl carbene intermediates. A distinct feature of this reaction is that the azavinyl carbene serves as a [2 C] equivalent, instead of as [1 C] or aza‐[3 C] synthons, which have been reported previously in cyclopropanations and [3+n] cycloadditions. Moreover, this methodology has also been successfully applied in the total synthesis of URB447 as well as the formal synthesis of Atorvastatin (Lipitor). 相似文献
11.
Highly Enantioselective [3+2] Cycloaddition of Vinylcyclopropane with Nitroalkenes Catalyzed by Palladium(0) with a Chiral Bis(tert‐amine) Ligand
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)
Feng Wei Chuan‐Li Ren Prof. Dr. Dong Wang Prof. Dr. Li Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2335-2338
An enantioselective [3+2] cycloaddition of vinyl cyclopropane derived from 1,3‐indanedione with nitroalkenes catalyzed by palladium(0) with a chiral bis(tert‐amine) ligand was developed in high yields with good diastereoselectivities and excellent enantioselectivities. The resulting bis(tert‐amine)–palladium complex proved to be a highly efficient catalyst for this cycloaddition. 相似文献
12.
A Catalytic Diastereoselective Formal [5+2] Cycloaddition Approach to Azepino[1,2‐a]indoles: Putative Donor–Acceptor Cyclobutanes as Reactive Intermediates
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)
Raynold Shenje M. Cynthia Martin Prof. Dr. Stefan France 《Angewandte Chemie (International ed. in English)》2014,53(50):13907-13911
A catalytic formal [5+2] cycloaddition approach to the diastereoselective synthesis of azepino[1,2‐a]indoles is reported. The reaction presumably proceeds through a Lewis acid catalyzed formal [2+2] cycloaddition of an alkene with an N‐indolyl alkylidene β‐amide ester to form a donor–acceptor cyclobutane intermediate, which subsequently undergoes an intramolecular ring‐opening cyclization. Azepine products are formed in up to 92 % yield with high degrees of diastereoselectivity (up to 34:1 d.r.). 相似文献
13.
Enantioselective Synthesis of [9]‐ and [11]Helicene‐like Molecules: Double Intramolecular [2+2+2] Cycloaddition
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)
Yuki Kimura Naohiro Fukawa Yuta Miyauchi Prof. Dr. Keiichi Noguchi Prof. Dr. Ken Tanaka 《Angewandte Chemie (International ed. in English)》2014,53(32):8480-8483
The enantioselective synthesis of completely ortho‐fused [9]‐ and [11]helicene‐like molecules has been achieved through a rhodium‐mediated, intramolecular, double [2+2+2] cycloaddition of phenol‐ or 2‐naphthol‐linked hexaynes. Crystal structures and photophysical properties of these [9]‐ and [11]helicene‐like molecules have also been disclosed. 相似文献
14.
Dr. Dong‐Chao Wang Dr. Ming‐Sheng Xie Prof. Dr. Hai‐Ming Guo Prof. Gui‐Rong Qu Meng‐Cheng Zhang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2016,55(45):14111-14115
A highly enantioselective dearomative [3+2] cycloaddition of benzothiazole has been successfully developed. A wide range of benzothiazoles and cyclopropane‐1,1‐dicarboxylates are suitable substrates for this reaction. The desired hydropyrrolo[2,1‐b]thiazole compounds were obtained in excellent enantioselectivity and yields (up to 97 % ee and 97 % yield). With the same catalytic system, a highly efficient kinetic resolution of 2‐substituted cyclopropane‐1,1‐dicarboxylates was also realized. 相似文献
15.
Brønsted Acid Catalyzed [3+2]‐Cycloaddition of 2‐Vinylindoles with In Situ Generated 2‐Methide‐2H‐indoles: Highly Enantioselective Synthesis of Pyrrolo[1,2‐a]indoles
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)
Dr. Kalisankar Bera Prof. Dr. Christoph Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7074-7078
Pyrrolo[1,2‐a]indoles are privileged structural elements of many natural products and pharmaceuticals. An efficient one‐step process for their highly diastereo‐ and enantioselective synthesis, comprising a direct [3+2]‐cycloaddition, has been developed. A chiral BINOL‐derived phosphoric acid catalyzes the reaction of in situ‐generated 2‐methide‐2H‐indoles with 2‐vinylindoles, furnishing the target products incorporating three contiguous stereogenic centers as single diastereoisomers and with excellent yields and enantioselectivities. 相似文献
16.
Stereoselective [3+2] Carbocyclization of Indole‐Derived Imines and Electron‐Rich Alkenes: A Divergent Synthesis of Cyclopenta[b]indole or Tetrahydroquinoline Derivatives
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)
Alicia Galván Dr. Jonás Calleja Dr. Adán B. González‐Pérez Prof. Dr. Rosana Álvarez Prof. Dr. Angel R. de Lera Prof. Dr. Francisco J. Fañanás Prof. Félix Rodríguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16769-16774
An unprecedented stereoselective [3+2] carbocyclization reaction of indole‐2‐carboxaldehydes, anilines, and electron‐rich alkenes to obtain cyclopenta[b]indoles is disclosed. This pathway is different from the well‐established Povarov reaction: the formal [4+2] cycloaddition involving the same components, which affords tetrahydroquinolines. Moreover, by simply changing the Brønsted acid catalyst, this multicomponent coupling process could be divergently directed towards the conventional Povarov pathway to produce tetrahydroquinolines or to the new pathway (anti‐Povarov) to generate cyclopenta[b]indoles. Supported by computational studies, a stepwise Mannich/Friedel–Crafts cascade is proposed for the new anti‐Povarov reaction, whereas a concerted [4+2] cycloaddition mechanism is proposed for the Povarov reaction. 相似文献
17.
Aromatic Amide‐Derived Non‐Biaryl Atropisomers as Highly Efficient Ligands in Silver‐Catalyzed Asymmetric Cycloaddition Reactions
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)
Xing‐Feng Bai Tao Song Dr. Zheng Xu Prof. Chun‐Gu Xia Wei‐Sheng Huang Prof. Dr. Li‐Wen Xu 《Angewandte Chemie (International ed. in English)》2015,54(17):5255-5259
The synthesis of a series of aromatic amide‐derived non‐biaryl atropisomers with a phosphine group and multiple stereogenic centers is reported. The novel phosphine ligands exhibit high diastereo‐ and enantioselectivities (up to >99:1 d.r., 95–99 % ee) as well as yields in the silver‐catalyzed asymmetric [3+2] cycloaddition of aldiminoesters with nitroalkenes, which provides a highly enantioselective strategy for the synthesis of optically pure nitro‐substituted pyrrolidines. In addition, the experimental results with regard to the carbon stereogenic center as well as the amide stereochemistry confirmed the potential of hemilabile atropisomers as chiral ligand in catalytic asymmetric [3+2] cycloaddition reaction. 相似文献
18.
Ring Expansion of Epoxides under Brønsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ‐Epoxy Esters with Imines Providing 2,4,5‐Trisubstituted 1,3‐Oxazolidines
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. Azusa Kondoh Kenta Odaira Prof. Dr. Masahiro Terada 《Angewandte Chemie (International ed. in English)》2015,54(38):11240-11244
A novel ring‐expansion reaction of epoxides under Brønsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ‐epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Brønsted base catalyst to afford 2,4,5‐trisubstituted 1,3‐oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Brønsted base catalyst to generate α,β‐unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3‐dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3‐oxazolidines from easily accessible enantioenriched epoxides. 相似文献
19.
Bowen Zhang Huw M. L. Davies 《Angewandte Chemie (International ed. in English)》2020,59(12):4937-4941
The reaction of 2‐siloxycyclo‐1,3‐dienes with E‐vinyldiazoacetates in the presence of the bulky chiral dirhodium tetracarboxylate catalyst, Rh2(R‐p‐PhTPCP)4 results in an enantioselective [4+2] cycloaddition, in which three new stereogenic centers are formed. The [4+2] cycloadducts are generated as single diastereomers with high enantiocontrol (95–98 % ee). When the diene contains an additional stereogenic center, effective kinetic resolution can be achieved. 相似文献
20.
Dr. Xiaoyu Han Wai‐Lun Chan Dr. Weijun Yao Dr. Yongjiang Wang Prof. Dr. Yixin Lu 《Angewandte Chemie (International ed. in English)》2016,55(22):6492-6496
Phosphine‐catalyzed enantioselective annulation reactions involving ketimines are a daunting synthetic challenge owing to the intrinsic low reactivity of ketimine substrates. A highly enantioselective [3+2] cycloaddition reaction that makes use of isatin‐derived ketimines as reaction partners was developed. Notably, both simple and γ‐substituted allenoates could be utilized, and various 3,2′‐pyrrolidinyl spirooxindoles with a tetrasubstituted stereocenter were obtained in excellent yields and with nearly perfect enantioselectivity (>98 % ee in all cases). 相似文献