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1.
Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)2? CuI combination (dba, dibenzylideneacetone) in DMF or copper(I) iodide in DMSO–THF readily catalyzes or mediates the coupling reaction of (Z)‐silyl(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group β to silicon with cis ‐disposition in good yields. Allyl chlorides as halides can be used in the CuI‐mediated reaction. CuI alone much more effectively mediates the cross‐coupling reaction with propargyl bromide in DMSO–THF at room temperature compared with a Pd(dba)2? CuI combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group β to silicon with cis ‐disposition in good yields. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
2.
Hiroaki Chiba Yuki Sakai Ayako Ohara Dr. Shinya Oishi Prof. Dr. Nobutaka Fujii Prof. Dr. Hiroaki Ohno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(27):8875-8883
The total synthesis of the pentacyclic tetrahydroisoquinoline alkaloid quinocarcin, which possesses intriguing structural and biological features, has been achieved through a gold(I)‐catalyzed regioselective hydroamination reaction. It is noteworthy that the regioselectivity of the intramolecular hydroamination of an unsymmetrical alkyne could be completely switched through substrate control. Other key features of this synthesis include the highly stereoselective synthesis of 2,5‐cis‐pyrrolidine through the intramolecular amination of the bromoallene and the Lewis acid mediated ring opening of dihydrobenzofuran. 相似文献
3.
Fatemeh Esmaeili‐Marandi Issa Yavari Mina Saeedi Mohammad Mahdavi Abbas Shafiee 《Helvetica chimica acta》2016,99(3):187-190
Novel derivatives of pyrazino[2,1‐a]isoindolediones were synthesized through 6‐exo‐dig intramolecular hydroamination of 2,3‐dihydro‐3‐oxo‐2‐(prop‐2‐yn‐1‐yl)‐1H‐isoindole‐1‐carboxamides followed by 1,3‐H shift, in the presence of sodium hydride in DMF at 80°. All products were obtained in good yields (60 – 80%) within short reaction time (40 – 60 min). 相似文献
4.
Fanke Meng Hwanjong Jang Prof. Amir H. Hoveyda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3204-3214
An exceptionally site‐ and E‐selective catalytic method for preparation of Si‐containing alkenes through protosilylation of terminal alkynes is presented. Furthermore, the vinylsilanes obtained are used as substrates to generate vicinal or geminal borosilanes by another catalytic process; such products are derived from enantioselective protoborations of the Si‐substituted alkenes. All transformations are catalyzed by N‐heterocyclic carbene (NHC) copper complexes. Specifically, a commercially available imidazolinium salt, cheap CuCl (1.0 mol %) and Me2PhSi–B(pin), readily and inexpensively prepared in one vessel, are used to convert terminal alkynes to (E)‐β‐vinylsilanes efficiently (79–98 % yield) and in >98 % E and >98 % β‐selectivity. Vinylsilanes are converted to borosilanes with 5.0 mol % of a chiral NHC–Cu complex in 33–94 % yield and up to 98.5:1.5 enantiomeric ratio (e.r.). Alkyl‐substituted substrates afford vicinal borosilanes exclusively; aryl‐ and heteroaryl‐substituted alkenes deliver the geminal isomers preferentially. Different classes of chiral NHCs give rise to high enantioselectivities in the two sets of transformations: C1‐symmetric monodentate Cu complexes are most suitable for reactions of alkyl‐containing vinylsilanes and bidentate sulfonate‐bridged variants furnish the highest e.r. for substrates with an aryl substituent. Working models that account for the observed trends in selectivity are provided. Utility is demonstrated through application towards a formal enantioselective total synthesis of naturally occurring antibacterial agent bruguierol A. 相似文献
5.
Hans A. Laub Prof. Dr. Herbert Mayr 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):1103-1110
Kinetics of the reactions of benzhydrylium ions (Aryl2CH+) with the vinylsilanes H2C?C(CH3)(SiR3), H2C?C(Ph)(SiR3), and (E)‐PhCH?CHSiMe3 have been measured photometrically in dichloromethane solution at 20 °C. All reactions follow second‐order kinetics, and the second‐order rate constants correlate linearly with the electrophilicity parameters E of the benzhydrylium ions, thus allowing us to include vinylsilanes in the benzhydrylium‐based nucleophilicity scale. The vinylsilane H2C?C(CH3)(SiMe3), which is attacked by electrophiles at the CH2 group, reacts one order of magnitude faster than propene, indicating that α‐silyl‐stabilization of the intermediate carbenium ion is significantly weaker than α‐methyl stabilization because H2C?C(CH3)2 is 103 times more reactive than propene. trans‐β‐(Trimethylsilyl)styrene, which is attacked by electrophiles at the silylated position, is even somewhat less reactive than styrene, showing that the hyperconjugative stabilization of the developing carbocation by the β‐silyl effect is not yet effective in the transition state. As a result, replacement of vinylic hydrogen atoms by SiMe3 groups affect the nucleophilic reactivities of the corresponding C?C bonds only slightly, and vinylsilanes are significantly less nucleophilic than structurally related allylsilanes. 相似文献
6.
Enantiodivergent Synthesis of (+)‐ and (−)‐Pyrrolidine 197B: Synthesis of trans‐2,5‐Disubstituted Pyrrolidines by Intramolecular Hydroamination
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Dr. Sixto J. Pérez Dr. Martín A. Purino Daniel A. Cruz Juan M. López‐Soria Dr. Rubén M. Carballo Prof. Miguel A. Ramírez Dr. Israel Fernández Prof. Víctor S. Martín Dr. Juan I. Padrón 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15529-15535
A highly efficient, diastereoselective, iron(III)‐catalyzed intramolecular hydroamination/cyclization reaction involving α‐substituted amino alkenes is described. Thus, enantiopure trans‐2,5‐disubstituted pyrrolidines and trans‐5‐substituted proline derivatives were synthesized by means of a combination of enantiopure starting materials, easily available from l ‐α‐amino acids, with sustainable metal catalysts such as iron(III) salts. The scope of this methodology is highlighted in an enantiodivergent approach to the synthesis of both (+)‐ and (?)‐pyrrolidine 197B alkaloids from l ‐glutamic acid. In addition, a computational study was carried out to gain insight into the complete diastereoselectivity of the transformation. 相似文献
7.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(15):4392-4396
A cobalt‐catalyzed Z ‐selective hydrosilylation of alkynes has been developed relying on catalysts generated from bench‐stable Co(OAc)2 and pyridine‐2,6‐diimine (PDI) ligands. A variety of functionalized aromatic and aliphatic alkynes undergo this transformation, yielding Z ‐vinylsilanes in high yields with excellent selectivities (Z /E ratio ranges from 90:10 to >99:1). The addition of a catalytic amount of phenol effectively suppressed the Z /E ‐isomerization of the Z ‐vinylsilanes that formed under catalytic conditions. 相似文献
8.
Copper(II)‐Catalyzed Silylation of Activated Alkynes in Water: Diastereodivergent Access to E‐ or Z‐β‐Silyl‐α,β‐Unsaturated Carbonyl and Carboxyl Compounds
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Joseph A. Calderone Prof. Dr. Webster L. Santos 《Angewandte Chemie (International ed. in English)》2014,53(16):4154-4158
Copper(II)‐catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me2PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products. 相似文献
9.
Synthesis of 1‐silacyclopent‐2‐ene derivatives using 1,2‐hydroboration, 1,1‐organoboration and protodeborylation
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The reaction of di(alkyn‐1‐yl)vinylsilanes R1(H2C═CH)Si(C≡C―R)2 (R1 = Me ( 1 ), Ph ( 2 ); R = Bu (a), Ph (b), Me2HSi (c)) at 25°C with 1 equiv. of 9‐borabicyclo[3.3.1]nonane (9‐BBN) affords 1‐silacyclopent‐2‐ene derivatives ( 3a , 3b , 3c , 4a , 4b ), bearing one Si―C≡C―R function readily available for further transformations. These compounds are formed by consecutive 1,2‐hydroboration followed by intramolecular 1,1‐carboboration. Treated with a further equivalent of 9‐BBN in benzene they are converted at relatively high temperature (80–100°C) into 1‐alkenyl‐1‐silacyclopent‐2‐ene derivatives ( 5a , 5b 6a , 6b ) as a result of 1,2‐hydroboration of the Si―C≡C―R function. Protodeborylation of the 9‐BBN‐substituted 1‐silacyclopent‐2‐ene derivatives 3 , 4 , 5 , 6 , using acetic acid in excess, proceeds smoothly to give the novel 1‐silacyclopent‐2‐ene ( 7 , 8 , 9 , 10 ). The solution‐state structural assignment of all new compounds, i.e. di(alkyn‐1‐yl)vinylsilanes and 1‐silacyclopent‐2‐ene derivatives, was carried out using multinuclear magnetic resonance techniques (1H, 13C, 11B, 29Si NMR). The gas phase structures of some examples were calculated and optimized by density functional theory methods (B3LYP/6‐311+G/(d,p) level of theory), and 29Si NMR parameters were calculated (chemical shifts δ29Si and coupling constants nJ(29Si,13C)). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
10.
Base‐Catalyzed Intramolecular Hydroamination of Cyclohexa‐2,5‐dienes: Insights into the Mechanism through DFT Calculations and Application to the Total Synthesis of epi‐Elwesine
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Dr. Géraldine Rousseau Dr. Raphaël Lebeuf Dr. Kurt Schenk Dr. Frédéric Castet Dr. Frédéric Robert Prof. Dr. Yannick Landais 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14771-14782
The base‐catalyzed intramolecular hydroamination of 1‐ethylaminocyclohexa‐2,5‐dienes is described. The transformation proceeds through isomerization of the cyclohexa‐1,4‐dienyl fragment into the corresponding conjugated 1,3‐diene prior to the hydroamination step. Attaching a chiral glycinol ether auxiliary on the amino group allows the protonation to occur with complete diastereocontrol. The resulting lithium amide then adds onto the 1,3‐dienyl moiety, affording the desired fused pyrrolidine ring along with the corresponding lithium allylic anion. Protonation of the latter then proceeds with high regiocontrol to favor the resulting allylic amines. In contrast, when the reaction was performed on primary amines, fused pyrrolidines bearing a homoallylic amino group were obtained. The stereochemical course of the process and determination of the reaction pathways were established based on calculations performed at the DFT level. Finally, application of the methodology to the enantioselective synthesis of (+)‐epi‐elwesine, a crinane alkaloid, is described. 相似文献
11.
Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)‐α‐silylvinyl Grignard reagents 2 , which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)‐α‐silylvinyl sulfides 4 in good yields. (E)‐α‐Silylvinyl sulfides 4 could undergo the cross‐coupling reactions with Grignard reagents in the presence of NiCl2(PPh3)2 to give stereoselectively (Z)‐1,2‐disubstituted vinylsilanes 5 . © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:644–647, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20165 相似文献
12.
anti‐Markovnikov Hydroamination of Alkenes Catalyzed by a Two‐Component Organic Photoredox System: Direct Access to Phenethylamine Derivatives
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Tien M. Nguyen Namita Manohar Prof. David A. Nicewicz 《Angewandte Chemie (International ed. in English)》2014,53(24):6198-6201
Disclosed herein is a general catalytic system for the intermolecular anti‐Markovnikov hydroamination of alkenes. By using an organocatalytic photoredox system, α‐ and β‐substituted styrenes as well as aliphatic alkenes undergo anti‐Markovnikov hydroamination. Heterocyclic amines were also successfully employed as nitrogen nucleophiles, thus providing a direct route to heterocyclic motifs common in medicinal agents. 相似文献
13.
Jacob C. Timmerman Bradley D. Robertson Prof. Ross A. Widenhoefer 《Angewandte Chemie (International ed. in English)》2015,54(7):2251-2254
The cationic gold phosphine complex [{PCy2(o‐biphenyl)}Au(NCMe)]+SbF6? (Cy=cyclohexyl) catalyzes the intermolecular, anti‐Markovnikov hydroamination reaction of monosubstituted and cis‐ and trans‐disubstituted alkylidenecyclopropanes (ACPs) with imidazolidin‐2‐ones and other nucleophiles. This reaction forms 1‐cyclopropyl alkylamine derivatives in high yield and with high regio‐ and diastereoselectivity. NMR spectroscopic analysis of gold π‐ACP complexes and control experiments point to the sp hybridization of the ACP internal alkene carbon atom as controlling the regiochemistry of the ACP hydroamination reaction. 相似文献
14.
Dr. Chih‐Ming Chou Dr. Joyram Guin Dr. Christian Mück‐Lichtenfeld Prof. Dr. Stefan Grimme Prof. Dr. Armido Studer 《化学:亚洲杂志》2011,6(5):1197-1209
An efficient synthesis of N‐phthalimidyl, benzamidyl, acetamidyl, carbamoyl, and ureayl derivatives of dihydropyridines and the application of these reagents as precursors for N‐centered radicals are presented. These aminated dihydropyridines could be used in radical‐transfer hydroamination reactions of various electron‐rich as well as nonactivated olefins in the presence of thiols as polarity‐reversal catalysts. These reactions worked without the aid of any transition metal. Steric and electronic effects exerted by the N‐substitutents of the N‐centered radicals are discussed. In contrast to most metal‐catalyzed processes, the radical hydroamination delivered the opposite regioisomer with excellent anti‐Markovnikov selectivity. Hydroamination products were obtained as protected amines that are readily isolated. 相似文献
15.
Xi‐Jie Dai Oliver D. Engl Thierry Len Stephen L. Buchwald 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3445-3449
Herein, we report a practical two‐step synthetic route to α‐arylpyrrolidines through Suzuki–Miyaura cross‐coupling and enantioselective copper‐catalyzed intramolecular hydroamination reactions. The excellent stereoselectivity and broad scope for the transformation of substrates with pharmaceutically relevant heteroarenes render this method a practical and versatile approach for pyrrolidine synthesis. Additionally, this intramolecular hydroamination strategy facilitates the asymmetric synthesis of tetrahydroisoquinolines and medium‐ring dibenzo‐fused nitrogen heterocycles. 相似文献
16.
Ruthenium‐Catalyzed Multicomponent Reactions: Access to α‐Silyl‐β‐Hydroxy Vinylsilanes,Stereodefined 1,3‐Dienes,and Cyclohexenes
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Prof. Dr. Barry M. Trost Dr. Dennis C. Koester Dr. Ehesan U. Sharif 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(8):2634-2638
The synthesis of densly functionized α‐silyl‐β‐hydroxyl vinylsilanes via ruthenium‐catalyzed multicomponent reaction (MCR) is reported herein. Exceptionally high regio‐ and diastereoselectivity was achieved by employing an unprecedented hydrosilylation of bifunctional silyl‐propargyl boronates. The simple protocol, mild reaction conditions, and unique tolerability of this method make it a valuable tool for the synthesis of highly elaborated building blocks. The one‐pot synthesis of stereodefined olefins, the generation of a valuable cyclohexene building block through a four‐component MCR, and further functionalization in an abundance of diastereoselective reactions is disclosed herein. 相似文献
17.
Kodai Kato Prof. Dr. Koji Hirano Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2016,55(46):14400-14404
A copper‐catalyzed regioselective and stereospecific aminoboration of vinylsilanes with bis(pinacolato)diboron (pinB‐Bpin) and hydroxylamines has been developed. In the presence of a CuCl/MeO‐dppbz catalyst, the boryl group and amino group are incorporated at the β position and α position, respectively, and the corresponding β‐boryl‐α‐aminosilanes are obtained with good diastereoselectivity. The boryl group is a good latent functional group, and subsequent manipulations provide a variety of β‐functionalized α‐aminosilanes of great potential in medicinal chemistry. Additionally, preliminary application to asymmetric catalysis is also described. 相似文献
18.
Beibei Li Zhanfeng Ju Mi Zhou Kongzhao Su Daqiang Yuan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7769-7773
The exploitation of new and active earth‐abundant metal catalysts is critical for sustainable chemical production. Herein, we demonstrate the design of highly efficient, robust, and reusable ZnII‐bipyridine‐based metal–organic framework (MOF) catalysts for the intramolecular hydroamination of o‐alkynylanilines to indoles. Under similar conditions homogeneous catalytic systems mainly provide hydrolysate. Our results prove that MOFs support unique internal environments that can affect the direction of chemical reactions. The ZnII‐catalyzed hydroamination reaction can be conducted without additional ligands, base, or acid, and is thus a very clean reaction system with regard to its environmental impact. 相似文献
19.
Several cobalt complexes bearing tridentate (NNN) ligands were synthesized and served as precatalysts for alkyne hydrosilylation with Ph2SiH2. For terminal alkynes, the catalyst L2 b‐CoCl2 was selected, and resulted in the corresponding α‐vinylsilanes with high (Markovnikov) regioselectivity and extensive functional‐group tolerance. For internal diaryl alkynes, the catalyst L2 c‐CoCl2 exhibited the best activity, and afforded E‐selective vinylsilanes through syn‐addition in excellent yield under mild conditions. 相似文献
20.
Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino‐Isocyanates
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Ryan A. Ivanovich Christian Clavette Jean‐François Vincent‐Rocan Jean‐Grégoire Roveda Dr. Serge I. Gorelsky Prof. Dr. André M. Beauchemin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7906-7916
The ubiquity of nitrogen heterocycles in biologically active molecules challenges synthetic chemists to develop a variety of tools for their construction. While developing metal‐free hydroamination reactions of hydrazine derivatives, it was discovered that carbazates and semicarbazides can also lead to alkene aminocarbonylation products if nitrogen‐substituted isocyanates (N‐isocyanates) are formed in situ as reactive intermediates. At first this reaction required high temperatures (150–200 °C), and issues included competing hydroamination and N‐isocyanate dimerization pathways. Herein, improved conditions for concerted intramolecular alkene aminocarbonylation with N‐isocyanates are reported. The use of βN‐benzyl carbazate precursors allows the effective minimization of N‐isocyanate dimerization. Diminished dimerization leads to higher yields of alkene aminocarbonylation products, to reactivity at lower temperatures, and to an improved scope for a reaction sequence involving alkene aminocarbonylation followed by 1,2‐migration of the benzyl group. Furthermore, fine‐tuning of the blocking (masking) group on the N‐isocyanate precursor, and reaction conditions relying on base catalysis for N‐isocyanate formation from simpler precursors resulted in room temperature reactivity, consequently minimizing the competing hydroamination pathway. Collectively, this work highlights that controlled reactivity of aminoisocyanates is possible, and provides a broadly applicable alkene aminocarbonylation approach to heterocycles possessing the β‐aminocarbonyl motif. 相似文献