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1.
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
2.
Dr. Tomoyuki Yoshimura Masatoshi Takuwa Keisuke Tomohara Makoto Uyama Dr. Kazuhiro Hayashi Pan Yang Ryuichi Hyakutake Dr. Takahiro Sasamori Prof. Dr. Norihiro Tokitoh Prof. Dr. Takeo Kawabata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15330-15336
β‐Lactams with contiguous tetra‐ and trisubstituted carbon centers were prepared in a highly enantioselective manner through 4‐exo‐trig cyclization of axially chiral enolates generated from readily available α‐amino acids. Use of a weak base (metal carbonate) in a protic solvent (EtOH) is the key to the smooth production of β‐lactams. Use of the weak base is expected to generate the axially chiral enolates in a very low concentration, which undergo intramolecular conjugate addition without suffering intermolecular side reactions. Highly strained β‐lactam enolates thus formed through reversible intramolecular conjugate addition (4‐exo‐trig cyclization) of axially chiral enolates undergo prompt protonation by EtOH in the reaction media (not during the work‐up procedure) to give β‐lactams in up to 97 % ee. 相似文献
3.
Abdullah S. Alshreimi Guanqun Zhang Tyler W. Reidl Ricardo L. Pea Nicholas‐George Koto Shahidul M. Islam Donald J. Wink Laura L. Anderson 《Angewandte Chemie (International ed. in English)》2020,59(35):15244-15248
A dearomative [3,3′]‐sigmatropic rearrangement that converts N‐alkenylbenzisoxazolines into spirocyclic pyrroline cyclohexadienones has been developed by using the dipolar cycloaddition of an N‐alkenylnitrone and an aryne to access these unusual transient rearrangement precursors. This cascade reaction affords spirocyclic pyrrolines that are inaccessible through dipolar cycloadditions of exocyclic cyclohexenones and provides a fundamentally new approach to novel spirocyclic pyrroline and pyrrolidine motifs that are common scaffolds in biologically‐active molecules. Diastereoselective functionalization processes have also been explored to demonstrate the divergent synthetic utility of the unsaturated spirocyclic products. 相似文献
4.
The reaction of racemic α‐keto β‐lactams 5a – 5c with the commercially available chiral compound trans‐4‐hydroxy‐L ‐proline ( 6 ) in the presence of a catalytic amount of Bi(NO3)3?5 H2O in EtOH gave a diastereoisomer mixture of β‐lactams with a pyrrole ring at C(3) ( 7 to 12 ). This is the first enantioselective synthesis of optically active β‐lactams (=azetidin‐2‐ones) that possess a pyrrolyl residue at C(3), in a single step. 相似文献
5.
Yi Ding Ye‐Qiang Han Le‐Song Wu Tao Zhou Qi‐Jun Yao Ya‐Lan Feng Ya Li Ke‐Xin Kong Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2020,59(33):14060-14064
Herein, we describe an unprecedented cascade reaction to β‐stereogenic γ‐lactams involving Pd(II)‐catalyzed enantioselective aliphatic methylene C(sp3)?H alkenylation–aza‐Wacker cyclization through syn‐aminopalladation. Readily available 3,3′‐substituted BINOLs are used as chiral ligands, providing the corresponding γ‐lactams with broad scope and high enantioselectivities (up to 98 % ee). 相似文献
6.
《中国化学》2018,36(7):612-618
Chiral β‐lactams and cyclobutanones are present in numerous natural and pharmaceutical products. The stereoselective construction of chiral four‐membered cyclic compounds is an ongoing challenge for the chemical community. Herein, we report a highly stereocontrolled construction of four‐membered ring (mini‐sized) β‐lactams and cyclobutanones via an Ir/ In‐BiphPHOX ‐catalyzed asymmetric hydrogenation, providing the corresponding optically active four‐membered ring carbonyl products bearing an α‐chiral carbon center with excellent yields (up to 99%) and enantioselectivities (up to 98%) under mild reaction conditions (1.0—2.5 bar H2 for 1.0—10 h). The reaction presents wide substrate scope. Diverse transformations of the catalyzed products were also conducted to show the potential utility of this protocol. 相似文献
7.
Catalytic Asymmetric Synthesis of Trifluoromethylated γ‐Amino Acids through the Umpolung Addition of Trifluoromethyl Imines to Carboxylic Acid Derivatives
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Novel cinchona alkaloid derived chiral phase‐transfer catalysts enabled the highly chemo‐, regio‐, diastereo‐, and enantioselective umpolung addition of trifluoromethyl imines to α,β‐unsaturated N‐acyl pyrroles. With a catalyst loading ranging from 0.2 to 5.0 mol %, this new catalytic asymmetric transformation provides facile and high‐yielding access to highly enantiomerically enriched chiral trifluoromethylated γ‐amino acids and γ‐lactams. 相似文献
8.
Control of N‐Heterocyclic Carbene Catalyzed Reactions of Enals: Asymmetric Synthesis of Oxindole‐γ‐Amino Acid Derivatives
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Dr. Xiang‐Yu Chen Jia‐Wen Xiong Qiang Liu Sun Li He Sheng Dr. Carolina von Essen Prof. Dr. Kari Rissanen Prof. Dr. Dieter Enders 《Angewandte Chemie (International ed. in English)》2018,57(1):300-304
A strategy to control the switch between a non‐cycloaddition reaction and a cycloaddition reaction of enals, using N‐heterocyclic carbene (NHC) catalyisis, has been developed. The new scalable protocol leads to γ‐amino‐acid esters bearing a tetrasubstituted stereocenter in good yields and high stereoselectivities by homo‐Mannich reactions of enals and isatin‐derived ketimines. By simply changing the N‐ketimine substituent to an ortho‐hydroxy phenyl group, the corresponding spirocyclic oxindolo‐γ‐lactams are obtained. 相似文献
9.
Jin‐Miao Tian Ai‐Fang Wang Ju‐Song Yang Xiao‐Jing Zhao Yong‐Qiang Tu Shu‐Yu Zhang Zhi‐Min Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11139-11143
A novel chiral 1,5‐N,N‐bidentate ligand based on a spirocyclic pyrrolidine oxazoline backbone was designed and prepared, and it coordinates CuBr in situ to form an unprecedented catalyst that enables efficient oxidative cross‐coupling of 2‐naphthols. Air serves as an external oxidant and generates a series of C1‐symmetric chiral BINOL derivatives with high enantioselectivity (up to 99 % ee) and good yield (up to 87 %). This approach is tolerant of a broader substrates scope, particularly substrates bearing various 3‐ and 3′‐substituents. A preliminary investigation using one of the obtained C1‐symmetric BINOL products was used as an organocatalyst, exhibiting better enantioselectivity than the previously reported organocatalyst, for the asymmetric α‐alkylation of amino esters. 相似文献
10.
Yoshihiko Yamamoto Prof. Dr. Ken Yamashita Tomitaka Hotta Toru Hashimoto Makoto Kikuchi Dr. Hisao Nishiyama Prof. Dr. 《化学:亚洲杂志》2007,2(11):1388-1399
Spirocyclic C‐arylglycosides were synthesized from the appropriately protected δ‐gluconolactones. Addition of lithium acetylide followed by glycosylation with 3‐(trimethylsilyl)propargyl alcohol converted the δ‐gluconolactones into silylated diynes. After desilylation, subsequent ruthenium‐catalyzed cycloaddition of the resultant diynes with alkynes or chloroacetonitrile gave spirocyclic C‐arylglycosides in good yields and selectivity. This strategy was also extended to the synthesis of spirocyclic C‐arylribosides from the known γ‐ribonolactone derivative. Moreover, silver‐catalyzed iodination of the sugar diynes followed by ruthenium‐catalyzed cycloaddition with acetylene delivered spirocyclic C‐iodophenylglycosides and ‐ribosides, which were subjected to palladium‐catalyzed C? C bond‐forming reactions and copper‐catalyzed coupling with nitrogen heterocycles to lead to various derivatives. 相似文献
11.
Nathalie Pinto Mathilde Neel Armen Panossian Dr. Pascal Retailleau Dr. Gilles Frison Dr. Arnaud Voituriez Dr. Angela Marinetti Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(3):1033-1045
The planar chiral 2‐phospha[3]ferrocenophane I has been shown to be the first efficient nucleophilic organocatalyst for the enantioselective synthesis of cyclopentenylphosphonates, through [3+2] cyclizations between diethyl allenylphosphonate and α,β‐unsaturated ketones. The same catalyst has also been applied to the highly enantioselective [3+2] cyclizations of allenic esters with dibenzylideneacetone and analogous bis‐enones, leading to functionalised cyclopentenes with either monocyclic or spirocyclic structures (ee 84–95 %). It has been shown that the residual enone functions in the resulting cyclopentenes can be involved in subsequent cyclization steps to afford unprecedented C2‐symmetric bis‐cyclopentenylketones. In order to provide insight into the behaviour of FerroPHANE I as a chiral catalyst in [3+2] cyclisations, the energetically most favoured isomers of the key phosphine‐allene adduct have been calculated by DFT methods. Factors likely to control the chiral induction process are highlighted. 相似文献
12.
《Journal of heterocyclic chemistry》2018,55(1):91-96
Reaction of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione ( 1 ) with two equivalents of some 6‐aminouracils (or 6‐amino‐2‐thiouracil) generates spirocyclic tetrahydrobenzo[if]quinolizines ( 7 ). The one‐pot, three‐component reaction of amido ketone ( 1 ) with 6‐aminouracil (or 6‐amino‐2‐thiouracil) and a cyclic six‐membered 1,3‐diketone produces spirocyclic tetrahydropyrrolo[3,2,1‐ij]quinolinones ( 15 ). 相似文献
13.
Catalytic Enantioselective Synthesis of C1‐ and C2‐Symmetric Spirobiindanones through Counterion‐Directed Enolate C‐Acylation
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Benjamin F. Rahemtulla Hugh F. Clark Prof. Dr. Martin D. Smith 《Angewandte Chemie (International ed. in English)》2016,55(42):13180-13183
A catalytic enantioselective route to C1‐ and C2‐symmetric 2,2′‐spirobiindanones has been realized through an intramolecular enolate C‐acylation. This reaction employs a chiral ammonium counterion to direct the acylation of an in situ generated ketone enolate with a pentafluorophenyl ester. This reaction constitutes the first example of a direct catalytic enantioselective C‐acylation of a ketone and provides an efficient and highly enantioselective route to axially chiral spirobiindanediones. These products can be diastereoselectively derivatized, offering access to a range of functionalized spirocyclic architectures. 相似文献
14.
Sandra Hübner Dirk Michalik Dr. Haijun Jiao Dr. Helfried Neumann Dr. Stefan Klaus Dirk Strübing Dr. Anke Spannenberg Dr. Matthias Beller Prof. Dr. 《化学:亚洲杂志》2007,2(6):734-746
Chiral N‐dienyl lactams are crucial building blocks for the synthesis of complex organic compounds. However, their generation is rather challenging. This paper reports the novel one‐pot reaction of (S)‐methyl pyroglutamate as the a mide component with different a ldehydes and d ienophiles (AAD reaction) to give novel chiral 1‐amido‐2‐cyclohexenes. The corresponding N‐dienyl lactams generated in situ undergo subsequent Diels–Alder reactions in good yield and diastereoselectivity. The scope and limitations of the three‐component protocol were investigated. X‐ray and NMR spectroscopic analysis of the products as well as DFT calculations of the intermediates were also performed to explain the observed stereoselectivity and structural features. 相似文献
15.
Manganese(III)‐promoted cyclization of N‐alkenylmalonamides (=N‐alkenylpropanediamides) gave 3‐(aryl/(alkylamino)carbonyl) β‐lactams as well as 3‐(aryl/(alkylamino)thiocarbonyl) β‐lactams. The relative configuration of the obtained products was unambiguously determined by X‐ray crystallography. The proposed method is very useful for the one‐pot synthesis of a number of 3‐(aryl/(alkylamino)carbonyl) β‐lactams, especially those containing an amino(thiocarbonyl) moiety, which are not selectively accessible by other methods. 相似文献
16.
Enantioselective Alkylation of N‐Arylhydrazones Derived from α‐Keto Esters and Isatin Derivatives through Asymmetric Phase‐Transfer Catalysis
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Dr. Qi‐Kai Kang Dr. Sermadurai Selvakumar Prof. Dr. Natarajan Arumugam Prof. Dr. Abdulrahman I. Almansour Prof. Dr. Raju Suresh Kumar Prof. Dr. Keiji Maruoka 《化学:亚洲杂志》2018,13(14):1780-1783
The phase‐transfer‐catalyzed asymmetric alkylation reactions of N‐arylhydrazones derived from α‐keto‐esters and isatin derivatives afford enantioenriched azo compounds that bear a tetra‐substituted carbon stereocenter in good yields with high chemo‐ and enantioselectivity. The alkylation products can be readily converted into chiral amino esters, hydrazine derivatives, and aza‐β‐lactams without loss of enantiopurity. 相似文献
17.
Enantioselective Formation of 2‐Azetidinones by Ring‐Assisted Cyclization of Interlocked N‐(α‐Methyl)benzyl Fumaramides
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Dr. Alberto Martinez‐Cuezva Dr. Delia Bautista Prof. Dr. Mateo Alajarin Dr. Jose Berna 《Angewandte Chemie (International ed. in English)》2018,57(22):6563-6567
The synthesis of optically active interlocked and non‐interlocked 2‐azetidinones by intramolecular cyclization of N‐(α‐methyl)benzyl fumaramide [2]rotaxanes is described. Two different strategies of asymmetric induction were tested in which the chiral group was located either proximal or distal to the reacting center of the thread. During these experiments, an interesting equilibration process inside the macrocyclic void occurred, thus leading to the cyclization through the (α‐methyl)benzyl carbon atom and giving rise to β‐lactams, with a quaternary carbon atom, in an enantio‐ and diastereocontrolled manner. This cyclization also proceeds in kinetically stable chiral pseudo[2]rotaxanes, thus allowing further dethreading to provide enantioenriched 3,4‐disubstituted trans‐2‐azetidinones. The stereochemical outcomes of the cyclizations inside and outside the macrocycle demonstrated noticeable differences. 相似文献
18.
N. Chary Mamillapalli Prof. Govindasamy Sekar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18584-18588
Synthesis of enantiomerically enriched α‐hydroxy amides and β‐amino alcohols has been accomplished by enantioselective reduction of α‐keto amides with hydrosilanes. A series of α‐keto amides were reduced in the presence of chiral CuII/(S)‐DTBM‐SEGPHOS catalyst to give the corresponding optically active α‐hydroxy amides with excellent enantioselectivities by using (EtO)3SiH as a reducing agent. Furthermore, a one‐pot complete reduction of both ketone and amide groups of α‐keto amides has been achieved using the same chiral copper catalyst followed by tetra‐n‐butylammonium fluoride (TBAF) catalyst in presence of (EtO)3SiH to afford the corresponding chiral β‐amino alcohol derivatives. 相似文献
19.
Jun Shen Naoto Ikeda Wanying Bi Kotaro Satoh Masami Kamigaito Yoshio Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):441-447
The asymmetric induction leading to a one‐handed helix was investigated in the anionic and radical copolymerization of triphenylmethyl methacrylate (TrMA) and (S)‐2‐isopropenyl‐4‐phenyl‐2‐oxazoline ((S)‐IPO), and highly isotactic copolymers with a reasonable optical activity were obtained. In the anionic copolymerization, the optical activity of the obtained copolymers depended on the polarity of solvents, and a highly optically active copolymer was produced in the copolymerization in toluene. The chiral oxazoline monomer functioned not only as a comonomer but also as a chiral ligand to endow the polymer with large negative optical rotation in the copolymerization with TrMA. The copolymers with small positive optical rotation were obtained in THF, indicating that IPO unit may work only as the chiral monomer that dictates the helical sense via copolymerization with TrMA. The isotacticity of the obtained copolymers depended on the contents of TrMA units in the copolymers, but was almost independent of the solvent for copolymerization. In the radical copolymerization, the obtained copolymers exhibited small optical activities. It seemed that the chiral monomer cannot induce one‐handed helical structure of TrMA sequences even if the sequences probably have a high isotacticity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 441–447 相似文献
20.
Synthesis of Spirocyclic Ethers by Enantioselective Copper‐Catalyzed Carboetherification of Alkenols
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Shuklendu D. Karyakarte Chanchamnan Um Ilyas A. Berhane Prof. Sherry R. Chemler 《Angewandte Chemie (International ed. in English)》2018,57(39):12921-12924
Spirocyclic ethers can be found in bioactive compounds. This copper‐catalyzed enantioselective alkene carboetherification provides 5,5‐, 5,6‐ and 6,6‐spirocyclic products containing fully substituted chiral carbon centers with up to 99 % enantiomeric excess. This reaction features the formation of two rings from acyclic substrates, 1,1‐disubstituted alkenols functionalized with either arenes, alkenes, or alkynes, and clearly constitutes a powerful way to synthesize chiral spirocyclic ethers. 相似文献