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1.
Enantioselective Desymmetrization of Prochiral Cyclohexanones by Organocatalytic Intramolecular Michael Additions to α,β‐Unsaturated Esters
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Adam D. Gammack Yamagata Dr. Swarup Datta Kelvin E. Jackson Linus Stegbauer Dr. Robert S. Paton Prof. Dr. Darren J. Dixon 《Angewandte Chemie (International ed. in English)》2015,54(16):4899-4903
A new catalytic asymmetric desymmetrization reaction for the synthesis of enantioenriched derivatives of 2‐azabicyclo[3.3.1]nonane, a key motif common to many alkaloids, has been developed. Employing a cyclohexanediamine‐derived primary amine organocatalyst, a range of prochiral cyclohexanone derivatives possessing an α,β‐unsaturated ester moiety linked to the 4‐position afforded the bicyclic products, which possess three stereogenic centers, as single diastereoisomers in high enantioselectivity (83–99 % ee) and in good yields (60–90 %). Calculations revealed that stepwise C? C bond formation and proton transfer via a chair‐shaped transition state dictate the exclusive endo selectivity and enabled the development of a highly enantioselective primary amine catalyst. 相似文献
2.
A simple, one‐step, stereoconservative synthesis of diamine‐based peptidomimetics is described, by split‐Ugi multicomponent reaction, involving chiral N‐protected amino acids and α‐substituted isocyanoacetate. In particular, piperazine and bispidine (3,7‐diazabicyclo[3.3.1]nonane) are exploited as diamine components, bispidine being the first example of a sterically demanding bicyclic system employed in a split‐Ugi reaction. 相似文献
3.
Formal Synthesis of Sarain A: Intramolecular Cycloaddition of an Eight‐Membered Cyclic Nitrone to Construct the 2‐Azabicyclo[3.3.1]nonane Framework
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Dr. Takuya Higo Tomoya Ukegawa Dr. Satoshi Yokoshima Prof. Tohru Fukuyama 《Angewandte Chemie (International ed. in English)》2015,54(25):7367-7370
An enantioselective route to the tetracyclic skeleton of sarain A has been developed. Asymmetric reduction of an ynone introduced a chiral center which was transferred to the contiguous tertiary stereogenic centers through an Ireland–Claisen rearrangement. The 2‐azabicyclo[3.3.1]nonane framework was constructed by an unprecedented intramolecular cycloaddition of an eight‐membered cyclic nitrone. Using the steric bias of the bicyclic system, the quaternary carbon atom was constructed by a stereoselective aldol reaction. Further ring formations were performed by ring‐closing metathesis for the 13‐membered ring and an iodoamidation reaction for the pyrrolidine ring. The present synthesis has successfully provided an alternative route to the late‐stage intermediate of Overman’s synthesis. 相似文献
4.
Gold‐Catalyzed Cycloisomerization of Yne‐Vinylidenecyclopropanes: A Three‐Carbon Synthon for [3+2] Cycloadditions
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Wei Yuan Xiangying Tang Yin Wei Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3198-3204
A novel type of yne‐vinylidenecyclopropanes (VDCPs) has been synthesized and applied in gold‐catalyzed cycloisomerization reactions. It was found that these compounds can undergo an intramolecular cycloisomerization and perform as a three‐carbon synthon for [3+2] cycloaddition under gold catalysis to give fused [4.3.0] and [5.3.0] bicyclic derivatives and VDCP rearranged products in moderated to good yields under mild conditions. The substrate scope of these novel transformations has been explored and plausible reaction mechanisms have been presented on the basis of deuterium labeling experiments and DFT calculations. 相似文献
5.
Nan Li Tian‐Yi Wang Prof. Dr. Liu‐Zhu Gong Prof. Dr. Liming Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3585-3588
An unprecedented gold‐catalyzed multiple cascade reaction between 2‐alkynyl arylazides and alkynols has been developed, allowing for the step‐economical synthesis of pyrroloindolone derivatives with a wide range of structural diversity. In this reaction, the gold complex participates in triple catalysis in tandem fashion. Moreover, the efficient chirality transfer from optically pure alkynol substrates enables facile access to chiral pyrroloindolone derivatives with two stereogenic centers, including a quaternary one, with excellent levels of optical purity. 相似文献
6.
Nucleophile‐Dependent Regio‐ and Stereoselective Ring Opening of 1‐Azoniabicyclo[3.1.0]hexane Tosylate
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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
7.
Gold(I)‐Catalyzed Generation of the Two Components of a Formal [4+2] Cycloaddition Reaction for the Synthesis of Tetracyclic Pyrano[2,3,4‐de]chromenes
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Dr. Tamara Arto Prof. Dr. Francisco J. Fañanás Prof. Félix Rodríguez 《Angewandte Chemie (International ed. in English)》2016,55(25):7218-7221
Ortho‐Alkynylbenzaldehydes have been widely used to generate isochromenylium derivatives through gold‐catalyzed cycloisomerization. These isochromenylium derivatives have been exploited as formal diene derivatives for reactions with different dienophiles. Herein, we describe the behavior of ortho‐alkynylsalicylaldehydes, a particular case of ortho‐alkynylbenzaldehydes. The gold‐catalyzed cycloisomerization of ortho‐alkynylsalicylaldehydes delivers an unusual heterodiene derivative that reacts with electron‐rich alkenes through a formal [4+2] cycloaddition. In this reaction, both the diene and dienophile are generated in situ through gold‐catalyzed cycloisomerization of appropriate alkynamines or alkynols. This reaction was used to synthesize complex tetracyclic pyrano[2,3,4‐de]chromenes from two very simple starting materials (an ortho‐alkynylsalicylaldehyde and an alkynamine or alkynol) with complete atom economy and with selective formation of bonds, cycles, and stereocenters. 相似文献
8.
5-Hydroxy-1-phosphabicyclo[3.3.1]nonane A new approach to 1-phosphabicyclo[3.3.1]nonane compounds involves free-radical cyclization of 4-trimethylsilyloxy-4-phosphinomethyl-hepta-1.6-diene synthesized by the reaction of 2.2-diallyl-oxirane with KPH2 followed by trimethylsilylation. Trimethylsilyl groups are easily cleaved in boiling methanol forming 5-hydroxy-1-phosphabicyclo[3.3.1]nonanes. Silylated and desilylated bicyclic compounds are characterized by n.m.r. and i.r. data. 相似文献
9.
Slow hydrolysis and oxidation of (Z)‐9‐[1‐chlorodiphenylsilyl)‐2‐phenyl‐vinyl]‐9‐borabicyclo[3.3.1]nonane ( 1 ) afforded 9‐hydroxy‐9‐borabicyclo[3.3.1]nonane ( 2 ) and the bicyclic oxasilabora‐heptadecane B2(OSiPh2OSiPh2O)3 ( 3 ), both of which could be isolated as crystalline materials and studied by X‐ray analysis. Molecules of 2 are associated in the crystal lattice by O‐H‐O bridging. The molecular structure of the diborabicyclo[5.5.5]heptadecane 3 is built by 12‐membered rings with the boron atoms in bridge head positions. The gas phase structures of 2 ( 2a ) and of the parent 3a , B2(OSiH2OSiH2O)3, were optimized at the B3LYP/6‐311+G(d,p) level of theory. 相似文献
10.
Michael Weber Bernd Morgenstern Kaspar Hegetschweiler HelmutW. Schmalle 《Helvetica chimica acta》2001,84(3):571-578
(1R,5S,6S,8R)‐6,8,9‐Trihydroxy‐3‐oxo‐2,4‐diazabicyclo[3.3.1]nonan‐7‐ammonium chloride hydrate ( 3 Cl⋅H2O) and (1R,5S,6S,8R)‐7‐amino‐6,8,9‐trihydroxy‐2,4‐diazabicyclo[3.3.1]nonan‐3‐one ( 4 ) have been prepared, and their crystal structures have been determined from single‐crystal X‐ray diffraction data. Both compounds consist of a bicyclic skeleton with the three N‐atoms in an all‐cis‐1,3,5‐triaxial arrangement. Considerable repulsion between these axial N‐atoms is indicated by a significant distortion of the two cyclohexane chairs and by increased N⋅⋅⋅N distances. The lone pair of the free amino group of 4 is involved in intermolecular H‐bonding and is turned away from the adjacent carbonyl C‐atom of the urea moiety. The structural properties together with the observed reactivity do not provide any evidence for an intramolecular donor‐acceptor interaction between the carbonyl C‐ and the amine N‐atom. 相似文献
11.
Chiral Silver Phosphate Catalyzed Transformation of ortho‐Alkynylaryl Ketones into 1H‐Isochromene Derivatives through an Intramolecular‐Cyclization/Enantioselective‐Reduction Sequence
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Prof. Dr. Masahiro Terada Feng Li Dr. Yasunori Toda 《Angewandte Chemie (International ed. in English)》2014,53(1):235-239
The transformation of ortho‐alkynylaryl ketones through a cyclization/enantioselective‐reduction sequence in the presence of a chiral silver phosphate catalyst afforded 1H‐isochromene derivatives in high yield with fairly good to high enantioselectivity. An asymmetric synthesis of the 9‐oxabicyclo[3.3.1]nona‐2,6‐diene framework, which has been found in some biologically active molecules, is presented as a demonstration of the synthetic utility of this method. 相似文献
12.
Activation of α‐Diazocarbonyls by Organic Catalysts: Diazo Group Acting as a Strong N‐Terminal Electrophile
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Lei Li Jia‐Jia Chen Yi‐Jin Li Xiu‐Bin Bu Qun Liu Yu‐Long Zhao 《Angewandte Chemie (International ed. in English)》2015,54(41):12107-12111
For the first time α‐diazocarbonyls have been used as highly active N‐terminal electrophiles in the presence of bicyclic amidine catalysts. The C? N bond‐forming reactions of active methylene compounds as C nucleophiles with α‐diazocarbonyls as N‐terminal electrophiles proceed quickly under ambient conditions, in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), because of the formation of the reactive N‐terminal electrophilic intermediates. DBU activates both the active methylene and α‐diazocarbonyl. Importantly, this reaction is general for both active methylenes and α‐diazocarbonyls, and the activation mode will lead to new synthetic applications of α‐diazocarbonyls. 相似文献
13.
Clair Bilton Judith A. K. Howard N. N. Laxmi Madhavi Gautam R. Desiraju Frank H. Allen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1356-1358
The title compounds, C8H10O2, (I), and C12H14O2, (II), occurred as by‐products in the controlled synthesis of a series of bis(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P21/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclohexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent molecules, in the cyclohexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, Cmethylene—H?O(H) and Cmethyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here. 相似文献
14.
H. H. Abdel‐Razik 《中国化学会会志》2003,50(4):887-891
Pyrano[4,3‐d]pyrimidine derivative 3 was prepared by reaction of chlorocarbonyl isocyanate 1 with enaminonitrile 2 . Compound 3 reacted with nitrogen nucleophiles 4a‐f to afford 2‐substituted pyrido[4,3d]pyrimidine 5–8 , pyrimido[i]1,5a‐diaza‐9‐oxafluorene 9 and pyrimido[i]5a‐aza‐9‐thiafluorene 10 derivatives. Also, compound 3 reacted with active methylene compounds 4j to yield pyrimidine derivatives 14–16 which on reaction with EtONa 4k afforded 1,5,7‐triaza‐10‐oxaphenanthrene derivatives 17–19 . 相似文献
15.
Gold‐Catalyzed Cascade Reactions of Furan‐ynes with External Nucleophiles Consisting of a 1,2‐Rearrangement: Straightforward Synthesis of Multi‐Substituted Benzo[b]furans
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Ning Sun Xin Xie Prof. Dr. Yuanhong Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7514-7519
A gold‐catalyzed cycloisomerization of silyl‐protected 2‐(1‐alkynyl)‐2‐alken‐1‐(2‐furanyl)‐1‐ols with various nucleophiles including water, alcohol, aniline, sulfonamide, and electron‐rich arene has been developed. The method provides a highly efficient access to 5,7‐disubstituted or 2,5,7‐trisubstituted benzo[b]furans with a wide diversity of substituents under mild reaction conditions, which are not easily available by other methods. Remarkably, an interesting rearrangement of the alkyl group from C2 to the C3 position of the furan ring takes place during the cyclization process. The following gold‐assisted allylic substitution enables an elaboration of benzo[b]furans on its side chain of the C5 position with a wide range of functional groups. 相似文献
16.
Catalyst‐Free Convergent Approach for the Synthesis of Spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline
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I. R. Siddiqui Anushree Srivastava Pragati Rai Arjita Srivastava Anjali Srivastava 《Journal of heterocyclic chemistry》2015,52(5):1415-1420
Strategies to address mounting environmental concerns with current approaches include an operationally simple and highly efficient one‐pot three‐component approach for the synthesis of spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline derivatives, which has been developed via Huisgen zwitter ion intermediate. The significant advantages of this protocol are short reaction time, excellent yields, and facile formation of three new bonds in one operation from easily available starting materials. 相似文献
17.
Synergistic Catalysis: Metal/Proton‐Catalyzed Cyclization of Alkynones Toward Bicyclo[3.n.1]alkanones
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Prof. Dr. Shifa Zhu Qiaohui Zhang Kai Chen Prof. Dr. Huanfeng Jiang 《Angewandte Chemie (International ed. in English)》2015,54(32):9414-9418
A highly efficient and practical synergistically metal/proton‐catalyzed Conia–ene reaction for the synthesis of bicyclo[3.n.1]alkanones has been developed. This synergistic catalysis was successfully utilized in modifying natural compounds such as methyl dihydrojasmonate, α,β‐thujone, and 5α‐cholestan‐3‐one. Furthermore, the bridged carbonyl group of bicyclo[3.2.1]alkanones could be easily attacked by nucleophiles to give the ring‐opened cycloheptenone products or bicyclo[4.2.1]amide in excellent yields. These reactions provide rapid access to a diverse range of cyclic structures from simple starting materials or naturally occurring compounds. 相似文献
18.
The catalytic performance of the superparamagnetic nanocatalyst Fe3O4@SiO2@Sulfated boric acid as a green, recyclable, and acidic solid catalyst in the synthesis of chromeno[4,3,2‐de][1,6]naphthyridine derivatives has been studied. Chromeno[4,3,2‐de][1,6]naphthyridine derivatives via a pseudo four‐component reaction from aromatic aldehydes (1 mmol), malononitrile (2 mmol), and 2′‐hydroxyacetophenone in the presence of Fe3O4@SiO2@Sulfated boric acid (0.004 g) as a nanocatalyst in 3 mL of water as a green solvent at 80°C has been synthesized. The advantages of this method are higher product yields in shorter reaction times, easy recyclability and reusability of the catalyst, and easy work‐up procedures. The nanocatalyst was reused at least six times. The nanocatalyst retained its stability in the reaction, and after reusability, it was separated easily from the reaction by an external magnet. 相似文献
19.
Dirhodium(II)‐Catalyzed Annulation of Enoldiazoacetamides with α‐Diazoketones: An Efficient and Highly Selective Approach to Fused and Bridged Ring Systems
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Dr. Qing‐Qing Cheng Julietta Yedoyan Dr. Hadi Arman Prof. Dr. Michael P. Doyle 《Angewandte Chemie (International ed. in English)》2016,55(18):5573-5576
A dirhodium(II)‐catalyzed annulation reaction between two structurally different diazocarbonyl compounds furnishes the donor–acceptor cyclopropane‐fused benzoxa[3.2.1]octane scaffold with excellent chemo‐, regio‐, and diastereoselectivity under exceptionally mild conditions. The composite transformation occurs by [3+2]‐cycloaddition between donor–acceptor cyclopropenes generated from enoldiazoacetamides and carbonyl ylides formed from intramolecular carbene–carbonyl cyclization in one pot with one catalyst. The annulation products can be readily transformed into benzoxa[3.3.1]nonane and hexahydronaphthofuran derivatives with exact stereocontrol. This method allows the efficient construction of three fused and bridged ring systems, all of which are important skeletons of numerous biologically active natural products. 相似文献
20.
Maxim V. Musalov Vladimir A. Potapov Svetlana V. Amosova 《Molecules (Basel, Switzerland)》2021,26(10)
The efficient synthesis of a new family of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes in high yields has been developed based on 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion generated from bis-isothiouronium salt of 2,6-dibromo-9-selenabicyclo[3.3.1]nonane. The derivatives of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonane containing alkyl, allyl and benzyl moieties have been prepared in 90–99% yields by nucleophilic substitution of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion with alkyl, allyl and benzyl halides. The reaction of nucleophilic addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to alkyl propiolates afforded 2,6-di(vinylsulfanyl)-9-selenabicyclo[3.3.1]nonanes. The conditions for regio- and stereoselective addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to a triple bond of alkyl propiolates have been found. To date, not a single representative of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes has been described in the literature. 相似文献