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Novel Asymmetric Formylation of Aromatic Compounds: Enantioselective Synthesis of Formyl 7,8‐Dipropyltetrathia[7]helicenes 下载免费PDF全文
Dr. Julien Doulcet Dr. G. Richard Stephenson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13431-13436
Asymmetric formylation of aromatic compounds is virtually unexplored. We report the synthesis and evaluation of a library including 20 new chiral formamides in the kinetic resolution of 7,8‐dipropyltetrathia[7]helicene, affording the corresponding formyl‐ or diformylhelicenes in up to 73 % ee, making enantiopure compounds available by recrystallisation. With the N,N‐disubstituted formamides used in this study, the best enantioselectivity has been achieved with R1=iPr, R2=Me, R3=H, R4=1‐naphthyl or its 1‐pyrenyl equivalent. 相似文献
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Shuichi Nakamura 《化学:亚洲杂志》2019,14(9):1323-1330
2H‐Azirines are useful precursors for the synthesis of a variety of chiral aziridine and amine derivatives with a range of biological activities. Owing to the ring strain and the presence of a C=N double bond, 2H‐azirines are more reactive than other types of ketimine, and undergo a range of enantioselective reactions, including reduction and Diels–Alder reactions, as well as nucleophilic addition to the C=N double bond. Therefore, the enantioselective reactions of 2H‐azirines has become a hot topic, in particular within the last few years. In this Minireview, we focus on the enantioselective reactions of 2H‐azirines by using catalytic or stoichiometric amounts of chiral additives, the reaction mechanisms, and the applications of these reactions of 2H‐azirines and related compounds in organic synthesis. 相似文献
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Ring opening reactions of N‐sulfonyl aziridines by primary and secondary amines in silica gel (SG)‐water system were achieved, which provided a mild, practical and environmentally benign method to synthesize mono‐ and bis‐sulfonyl substituted amines. When primary and secondary amines were used in excess, they reacted with N‐sulfonyl aziridines smoothly at room temperature, mainly affording 1:1 ring opening products. Reactions of primary amines with 2 equiv. of aziridines produced 2:1 ring opening products. Some 1:1 products can be cyclized with CS2 to synthesize N‐sulfonyl cyclothioureas also in water. 相似文献
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Everton Machado da Silva Hrika Danielle Almeida Vidal Marcelo Augusto Pereira Janurio Arlene Gonalves Corrêa 《Molecules (Basel, Switzerland)》2023,28(1)
BINOL derivatives have shown relevant biological activities and are important chiral ligands and catalysts. Due to these properties, their asymmetric synthesis has attracted the interest of the scientific community. In this work, we present an overview of the most efficient methods to obtain chiral BINOLs, highlighting the use of metal complexes and organocatalysts as well as kinetic resolution. Further derivatizations of BINOLs are also discussed. 相似文献
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A Robust,Recyclable Resin for Decagram Scale Resolution of (±)‐Mefloquine and Other Chiral N‐Heterocycles 下载免费PDF全文
Imants Kreituss Dr. Kuang‐Yen Chen Dr. Simon H. Eitel Dr. Jean‐Michel Adam Dr. Georg Wuitschik Dr. Alec Fettes Prof. Dr. Jeffrey W. Bode 《Angewandte Chemie (International ed. in English)》2016,55(4):1553-1556
Decagram quantities of enantiopure (+)‐mefloquine have been produced via kinetic resolution of racemic mefloquine using a ROMP‐gel supported chiral acyl hydroxamic acid resolving agent. The requisite monomer was prepared in a few synthetic steps without chromatography and polymerization was safely performed on a >30 gram scale under ambient conditions. The reagent was readily regenerated and reused multiple times for the resolution of 150 grams of (±)‐mefloquine and other chiral N‐heterocylces. 相似文献
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Nucleophile‐Dependent Regio‐ and Stereoselective Ring Opening of 1‐Azoniabicyclo[3.1.0]hexane Tosylate 下载免费PDF全文
Mi‐Kyung Ji Dietmar Hertsen Doo‐Ha Yoon Heesung Eum Hannelore Goossens Prof. Dr. Michel Waroquier Prof. Dr. Veronique Van Speybroeck Prof. Dr. Matthias D'hooghe Prof. Dr. Norbert De Kimpe Prof. Dr. Hyun‐Joon Ha 《化学:亚洲杂志》2014,9(4):1060-1067
1‐[(1R)‐(1‐Phenylethyl)]‐1‐azoniabicyclo[3.1.0]hexane tosylate was generated as a stable bicyclic aziridinium salt from the corresponding 2‐(3‐hydroxypropyl)aziridine upon reaction with p‐toluenesulfonyl anhydride. This bicyclic aziridinium ion was then treated with various nucleophiles including halides, azide, acetate, and cyanide in CH3CN to afford either piperidines or pyrrolidines through regio‐ and stereoselective ring opening, mediated by the characteristics of the applied nucleophile. On the basis of DFT calculations, ring‐opening reactions under thermodynamic control yield piperidines, whereas reactions under kinetic control can yield both piperidines and pyrrolidines depending on the activation energies for both pathways. 相似文献
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Brinton Seashore‐Ludlow Piret Villo Prof. Peter Somfai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(23):7219-7223
Herein, we present two methods for an asymmetric transfer hydrogenation through the dynamic kinetic resolution of α‐amido‐β‐ketoesters. These procedures yield the corresponding anti‐β‐hydroxy‐α‐amido esters in good yields and with good diastereo‐ and enantioselectivities. First, the scope of the reduction of α‐amido‐β‐ketoesters by using triethylammonium formate azeotrope is examined. Then, an emulsion technology with sodium formate is explored, which allows for broader substrate scope, faster reaction times, and lower catalyst loading. Furthermore, these reactions are operationally simple and can be set up in air. 相似文献
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A Synthetic Route to Chiral Dihydrobenzothiazines through Ring Opening of Activated Aziridines with 2‐Halothiophenols/Copper‐Powder‐Mediated C−N Cyclization 下载免费PDF全文
Prof. Dr. Manas K. Ghorai Masthanvali Sayyad Yerramsetti Nanaji Sourita Jana 《化学:亚洲杂志》2015,10(7):1480-1489
A simple protocol for the synthesis of dihydrobenzothiazines through regio‐ and stereoselective SN2‐type ring opening of N‐tosylaziridines with sulfur nucleophiles followed by copper‐powder‐mediated intramolecular C?N cyclization in excellent yields (up to 95 %) with high diastereo‐ and enantioselectivity (up to >99 %) is reported. 相似文献
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Ming Gao Ye‐Cheng Wang Kai‐Rui Yang Dr. Wei He Prof. Dr. Xiao‐Liang Yang Prof. Dr. Zhu‐Jun Yao 《Angewandte Chemie (International ed. in English)》2018,57(40):13313-13318
The first and enantioselective total synthesis of (+)‐plumisclerin A, a novel unique complex cytotoxic marine diterpenoid, has been accomplished. Around the central cyclopentane anchorage, a sequential ring‐formation protocol was adopted to generate the characteristic tricycle[4.3.1.01,5]decane and trans‐fused dihyrdopyran moiety. Scalable enantioselective LaIII‐catalyzed Michael reaction, palladium(0)‐catalyzed carbonylation and SmI2‐mediated radical conjugate addition were successfully applied in the synthesis, affording multiple grams of the complex and rigid B/C/D‐ring system having six continuous stereogenic centers and two all‐carbon quaternary centers. The trans‐fused dihyrdopyran moiety with an exo side‐chain was furnished in final stage through sequential redox transformations from a lactone precursor, which overcome the largish steric strain of the dense multiring system. The reported total synthesis also confirms the absolute chemistries of natural (+)‐plumisclerin A. 相似文献
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Hiroto Uno Nagender Punna Etsuko Tokunaga Motoo Shiro Norio Shibata 《Angewandte Chemie (International ed. in English)》2020,59(21):8187-8194
The two enantiomers of trifluoromethyl‐benzo[c][1,5]oxazonines, (R)‐ 4 and (S)‐ 4 , can be selectively accessed with high enantiopurity by the Pd‐catalyzed ring‐expansion reaction of trifluoromethyl‐benzo[d][1,3]oxazinones ( 1 ) with vinyl ethylene carbonates ( 3 ) using one antipode of a chiral ligand. Initially, the reaction proceeds by a double decarboxylative ring‐expansion with kinetic resolution of 1 in the presence of a Pd‐catalyst/chiral ligand to provide (R)‐ 4 with high enantiopurity. At the same time, the nonreactive antipode of 1 , (S)‐ 1 , which was recovered with an impeccable s factor of up to 713 and an ideal chemical yield, was transferred into the antipode of the products, (S)‐ 4 , with high enantiopurity by a second run of the Pd‐catalyzed double decarboxylation reaction, but this time without any chiral auxiliary. Thus, both antipodes of the chiral trifluoromethyl heterocycles 4 can be obtained in excellent enantiopurity using only a single antipode of the chiral catalyst. 相似文献
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Yoshiaki Miyamoto Norihiro Wada Dr. Takahiro Soeta Dr. Shuhei Fujinami Prof. Dr. Katsuhiko Inomata Prof. Dr. Yutaka Ukaji 《化学:亚洲杂志》2013,8(4):824-831
The stereoselective direct transformation of N‐(propargylic)hydroxylamines into cis‐2‐acylaziridines was achieved by the combined use of AgBF4 and CuCl. Copper salts were found to promote the transformation of the intermediary 4‐isoxazolines into 2‐acylaziridines and both 3‐aryl‐ and 3‐alkyl‐substituted 2‐acylaziridines could be prepared by using this method. Furthermore, subsequent 1,3‐dipolar cycloaddition of azomethine ylides that were generated in situ from the intermediary 2‐acylaziridines with maleimides was achieved in a stereoselective one‐pot procedure to afford the corresponding 2‐acylpyrrolidines, which consisted of an octahydropyrrolo[3,4‐c]pyrrole skeleton. 相似文献
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Total Synthesis of Cryptocaryol A by Enantioselective Iridium‐Catalyzed Alcohol C−H Allylation 下载免费PDF全文
Dr. Felix Perez Andrew R. Waldeck Prof. Michael J. Krische 《Angewandte Chemie (International ed. in English)》2016,55(16):5049-5052
The polyketide natural product cryptocaryol A is prepared in 8 steps via iridium catalyzed enantioselective diol double C?H allylation, which directly generates an acetate‐based triketide stereodiad. In 4 previously reported total syntheses, 17–28 steps were required. 相似文献
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Enantioselective Oxidative Aerobic Dealkylation of N‐Ethyl Benzylisoquinolines by Employing the Berberine Bridge Enzyme 下载免费PDF全文
Somayyeh Gandomkar Eva‐Maria Fischereder Dr. Joerg H. Schrittwieser Dr. Silvia Wallner Dr. Zohreh Habibi Prof. Dr. Peter Macheroux Prof. Dr. Wolfgang Kroutil 《Angewandte Chemie (International ed. in English)》2015,54(50):15051-15054
N‐Dealkylation methods are well described for organic chemistry and the reaction is known in nature and drug metabolism; however, to our knowledge, enantioselective N‐dealkylation has not been yet reported. In this study, exclusively the (S)‐enantiomers of racemic N‐ethyl tertiary amines (1‐benzyl‐N‐ethyl‐1,2,3,4‐tetrahydroisoquinolines) were dealkylated to give the corresponding secondary (S)‐amines in an enantioselective fashion at the expense of molecular oxygen. The reaction is catalyzed by the berberine bridge enzyme, which is known for C? C bond formation. The dealkylation was demonstrated on a 100 mg scale and gave optically pure dealkylated products (ee>99 %). 相似文献
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Dipl. Chem. Miriam Mahler Dr. Bastian Reichardt Dr. Philip Hartjen Prof. Dr. Jan van Lunzen Prof. Dr. Chris Meier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(35):11046-11062
An efficient synthesis of (S)‐ or (R)‐3‐(benzyloxy‐methyl)‐cyclopent‐3‐enol was developed by appling an enzyme‐catalyzed kinetic‐resolution approach. This procedure allowed the syntheses of the enantiomeric building blocks (S)‐ and (R)‐cyclopentenol with high optical purity (>98 % ee). In contrast to previous approaches, the key advantage of this procedure is that the resolution is done on the level of enantiomers that only contain one stereogenic center. Owing to this feature, it was possible to chemically convert the enantiomers into each other. By using this route, the starting materials for the syntheses of carbocyclic D ‐ and L ‐nucleoside analogues were readily accessible. 3′,4′‐Unsaturated D ‐ or L ‐carbocyclic nucleosides were obtained from the condensation of various nucleobases with (S)‐ or (R)‐cyclopentenol. Functionalization of the double bond in 3′‐deoxy‐3′,4′‐didehydro‐carba‐D ‐thymidine led to a variety of new nucleoside analogues. By using the cycloSal approach, their corresponding phosphorylated metabolites were readily accessable. Moreover, a new synthetic route to carbocyclic 2′‐deoxy‐nucleosides was developed, thereby leading to D ‐ and L ‐carba‐dT. D ‐Carba‐dT was tested for antiviral activity against multidrug‐resistance HIV‐1 strain E2‐2 and compared to the known antiviral agent d4T, as well as L ‐carba‐dT. Whilst L ‐carba‐dT was found to be inactive, its D ‐analogue showed remarkably high activity against the resistant virus and significantly better than that of d4T. However, against the wild‐type virus strain NL4/3, d4T was found to be more‐active than D ‐carba‐dT. 相似文献