共查询到20条相似文献,搜索用时 78 毫秒
1.
Allison M. Bergmann Stanna K. Dorn Kevin B. Smith Kaitlyn M. Logan M. Kevin Brown 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1733-1737
Two methods are reported for the 1,2‐ and 1,1‐arylboration of α‐methyl vinyl arenes. In the case of 1,2‐arylboration, the formation of a quaternary center occurred through a rare cross‐coupling reaction of a tertiary organometallic complex. 1,1‐Arylboration was enabled by catalyst optimization and occurred through a β‐hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations. 相似文献
2.
Artem Cherepakha Vladimir O. Kovtunenko Andrey Tolmachev Oleg Lukin 《Journal of heterocyclic chemistry》2013,50(5):1071-1077
A set of synthetic procedures was developed to yield functionalized pyrido‐, pyrimido‐, and thiazo‐annulated thiadiazine‐1,1‐dioxides on a preparative scale. In all cases the thiadiazine‐1,1‐dioxide ring closure was carried out through a reaction of hetaryl‐sulfonyl chlorides with amidines under mild noncatalytic conditions. In the case of 2‐chloropyridine‐3‐sulfonyl chloride derivatives and 2,4‐dichlorothiazole‐5‐sulfonyl chloride open‐chain sulfonylated amidine intermediates were isolated and then subjected to the cyclization step. The reaction with 2,4‐dichloropyrimidine‐5‐sulfonyl chloride gave rise to the corresponding thiadiazine‐1,1‐dioxides in one‐pot. Similarly, a reaction of 2‐chloropyridine‐3‐sulfonamide with lactime ethers proceeded in one‐pot readily giving the corresponding thiadiazine‐1,1‐dioxides. Remaining chlorine atoms on the prepared hetaryl‐annulated benzothiadiazine‐1,1‐dioxides readily undergo aromatic nucleophilic displacement reactions serving thus as additional variation points for the design of biologically potent compounds. 相似文献
3.
The reactions of phosphorochloridites 5a–c with an equimolar amount of 1,2‐thiazetidine 1,1‐dioxide (2) or L(−)‐3‐carboethoxy‐1,2‐thiazetidine 1,1‐dioxide (7) in the presence of triethylamine, affords the N‐phosphitylated β‐sultams 6a–b and L(−)‐8a,c. Their oxidation by addition of oxygen, sulfur, or selenium results in formation of stable organophosphorus β‐sultams 10a–b, L(−)‐11a,c, 12a, 13a, L(−)‐14c, and L(−)‐15c. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 61–67, 1999 相似文献
4.
M.Teresa Barros AntnioS. Henriques AlcinoJ. Leito ChristopherD. Maycock 《Helvetica chimica acta》2002,85(11):4079-4085
The selective formation of optically active 2‐acyl‐2‐alkyl‐1,3‐dithiolane 1,1‐dioxides from the corresponding 2‐acyl‐2‐alkyl‐1,3‐dithiolane 1‐oxides, by reaction with OsO4 and NMO in acetone, is reported. These compounds underwent stereoselective reactions at the carbonyl group of the acyl group with organometallic reagents. These reactions were completely regioselective, and no attack at either of the S‐atoms was observed, unlike similar reactions with the corresponding sulfoxides. The nature of the metal atom had a direct effect upon the configuration of the product alcohols. 相似文献
5.
Junyu Dong Tianbin Li Chuan Dai Wen Weng Xinghua Xue Yuyu Zhang Qingle Zeng 《应用有机金属化学》2013,27(6):337-340
A straightforward, protecting‐group‐free protocol for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols (binol = 1,1’‐bi‐2‐naphthol) by palladium‐catalyzed hydroxylation, C–N and C–O coupling of chiral 6‐bromo‐ and 6,6’ ‐dibromo‐1,1’‐binaphthols is developed. The protecting group free palladium‐catalyzed hydroxylation, C–O and C–N cross‐coupling protocol affords a straightforward and general method for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols with good yields, avoiding the tedious procedures of introduction and removal of protecting groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
6.
Dr. Juri Möbus Dr. Anzhela Galstyan Andreas Feldmann Dr. Constantin G. Daniliuc Dr. Roland Fröhlich Dr. Cristian A. Strassert Dr. Gerald Kehr Prof. Dr. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11883-11893
In this study the scope of the 1,1‐carboboration reaction was extended to the preparation of mixed heterole‐based conjugated π‐systems. Two arylbis(alkynyl)phosphane starting materials 2 were synthesized bearing two thiophene isomers at the alkyne units and the bulky tipp‐substituent (tipp=2,4,6‐triisopropylphenyl) at the phosphorous atom. The bis(thienylethynyl)phosphanes 2 were converted into the corresponding 2,5‐thienyl‐substituted 3‐borylphospholes 4 in a double 1,1‐carboboration reaction sequence employing the strongly electrophilic B(C6F5)3 reagent under mild reaction conditions. Subsequent Suzuki–Miyaura type cross‐coupling yielded the corresponding 3‐phenylphospholes 7 in a one‐pot procedure from phosphanes 2 in high yields. Phospholes 7 were converted into the respective phosphole oxides 8 . A photophysical characterization of derivatives 7 and 8 was carried out. The results presented here demonstrate the suitability of the 1,1‐carboboration reaction for the preparation of phosphole‐/thiophene‐based, light‐emitting systems. 相似文献
7.
A novel facile photoconversion of 4‐hydroxy‐1,2‐bezothiazine 1,1‐dioxides ( 3a‐e ) into 4‐oxo‐1,3‐2H‐benzothiazine 1,1‐dioxides ( 4a‐e ) and 4‐hydroxy‐2‐methyl‐N‐(pyridin‐2‐yl)‐2H‐1,2‐benzothiazine‐3‐carboxamide 1,1‐dioxide (PRX) into N‐methyl saccharin ( 2 ) upon 254 nm irradiation in methanol or acetonitrile is reported. The structures of the products have been elucidated by spectroscopic methods and single crystal X‐ray structure determination for 4a and 4d . 相似文献
8.
Enantio‐ and Diastereoselective 1,2‐Additions to α‐Ketoesters with Diborylmethane and Substituted 1,1‐Diborylalkanes 下载免费PDF全文
Stephanie A. Murray Jacob C. Green Sanita B. Tailor Prof. Simon J. Meek 《Angewandte Chemie (International ed. in English)》2016,55(31):9065-9069
The catalytic enantioselective synthesis of boronate‐substituted tertiary alcohols through additions of diborylmethane and substituted 1,1‐diborylalkanes to α‐ketoesters is reported. The reactions are catalyzed by readily available chiral phosphine/copper(I) complexes and produce β‐hydroxyboronates containing up to two contiguous stereogenic centers in up to 99:1 e.r. and greater than 20:1 d.r. The utility of the organoboron products is demonstrated through several chemoselective functionalizations. Evidence indicates the reactions occur via an enantioenriched α‐boryl‐copper‐alkyl intermediate. 相似文献
9.
Nickel‐Catalyzed Difluoroalkylation of (Hetero)Arylborons with Unactivated 1‐Bromo‐1,1‐difluoroalkanes 下载免费PDF全文
Yu‐Lan Xiao Qiao‐Qiao Min Chang Xu Dr. Ruo‐Wen Wang Prof. Dr. Xingang Zhang 《Angewandte Chemie (International ed. in English)》2016,55(19):5837-5841
A nickel‐catalyzed cross‐coupling between (hetero)arylborons and unactivated 1‐bromo‐1,1‐difluoroalkanes has been developed. The use of two ligands (a bidentate bipyridine‐based ligand, 4,4′‐ditBu‐bpy, and a monodentate pyridine‐based ligand, DMAP) offers a highly efficient nickel‐based catalytic system to prepare difluoroalkylated arenes which have important applications in medicinal chemistry. 相似文献
10.
Dr. Dennis Fischer Prof. Dr. Thomas M. Klapötke Dr. Jörg Stierstorfer Norbert Szimhardt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4966-4970
1,1′‐Dinitramino‐5,5′‐bitetrazole and 1,1′‐dinitramino‐5,5′‐azobitetrazole were synthesized for the first time. The neutral compounds are extremely sensitive and powerful explosives. Selected nitrogen‐rich salts were prepared to adjust sensitivity and performance values. The compounds were characterized by low‐temperature X‐ray diffraction, IR and Raman spectroscopy, multinuclear NMR spectroscopy, elemental analysis, and DTA/DSC. Calculated energetic performances using the EXPLO5 code based on calculated (CBS‐4M) heats of formation and X‐ray densities support the high performances of the 1,1′‐dinitramino‐5,5′‐bitetrazoles as energetic materials. The sensitivities toward impact, friction, and electrostatic discharge were also explored. Most of the compounds show sensitivities in the range of primary explosives and should only be handled with great care! 相似文献
11.
StephenP. Thomas VarinderK. Aggarwal 《Angewandte Chemie (International ed. in English)》2009,48(11):1896-1898
A breakthrough in the asymmetric hydroboration of notoriously difficult 1,1‐disubstituted alkenes using a new family of highly effective hydroboration reagents is described (see scheme). The intermediate boranes can be oxidized to alcohols or used in Suzuki–Miyaura cross‐coupling reactions.
12.
Beln Rubial Beatrice S. L. Collins Raphael Bigler Stefan Aichhorn Adam Noble Varinder K. Aggarwal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1380-1384
The one‐pot sequential coupling of benzylamines, boronic esters, and aryl iodides has been investigated. In the presence of an N‐activator, the boronate complex formed from an ortho‐lithiated benzylamine and a boronic ester undergoes stereospecific 1,2‐metalate rearrangement/anti‐SN2′ elimination to form a dearomatized tertiary boronic ester. Treatment with an aryl iodide under palladium catalysis leads to rearomatizing γ‐selective allylic Suzuki–Miyaura cross‐coupling to generate 1,1‐diarylalkanes. When enantioenriched α‐substituted benzylamines are employed, the corresponding 1,1‐diarylalkanes are formed with high stereospecificity. 相似文献
13.
Metallacyclopentadienes and related heterocycles via 1,1‐organoboration of alkyn‐1‐ylmetal compounds
Bernd Wrackmeyer 《Heteroatom Chemistry》2006,17(3):188-208
Metallacyclopentadienes (metalloles) containing M = Si, Ge, Sn, Pb, Ti, Pt can be prepared by 1,1‐organoboration of alkyn‐1‐ylmetal compounds LnM CC R1(R1 = H, alkyl, aryl, silyl, etc; L depends on M, and can be hydrogen, alkyl, aryl, Cl, Br, amino groups, a chelating diphosphane, and one or more L can be again alkynyl groups). These reactions proceed via activation of the M C bond(s) by an electron‐deficient triorganoborane BR3 (R = alkyl, aryl; non‐cyclic, monocyclic, bicyclic, and tricyclic boranes), at first intermolecular and then intramolecular. In the course of these reactions, the M C bonds are cleaved, zwitterionic alkynylborate‐like intermediates are formed, in which the metal‐containing fragments are coordinated side‐on to the CC bonds. In most cases, the 1,1‐organoboration reactions tolerate various functional groups at the alkyne as well as at the metal. The characterization of intermediates and final products by X‐ray structural analysis and by multinuclear magnetic resonance spectroscopy (NMR) is documented and described. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:188–208, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20222 相似文献
14.
Reaction Optimization,Scalability, and Mechanistic Insight on the Catalytic Enantioselective Desymmetrization of 1,1‐Diborylalkanes via Suzuki–Miyaura Cross‐Coupling 下载免费PDF全文
Ho‐Yan Sun Koji Kubota Prof. Dennis G. Hall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19186-19194
A method for enantioselective desymmetrization of 1,1‐diborylalkanes through a stereoselective Pd‐catalyzed Suzuki–Miyaura cross‐coupling has been thoroughly optimized. The most effective ligand was found to be a α,α,α,α‐tetra‐aryl‐1,3‐dioxolane‐4,5‐dimethanol (TADDOL)‐derived phosphoramidite. Results show that in order to achieve high selectivity, a suitable balance between the sterics of the aryl groups and the amino group on the ligand must be achieved. While the base has been known to facilitate transmetallation in cross‐coupling reactions, mechanistic studies on this desymmetrization process reveal that the base, in the presence of KHF2, likely plays an additional role in the hydrolysis of the pinacol boronates to the corresponding boronic acids. Through an in depth optimization of the chiral ligand and mechanistic studies, it was possible to obtain ee values over 90 % for several aryl bromides and to develop a reliably scalable process (up to one gram of 1,1‐diborylalkane substrate). 相似文献
15.
Dr. Omrane Fadhel Dr. Zoltán Benkö Michael Gras Valérie Deborde Damien Joly Christophe Lescop Prof. László Nyulászi Prof. Muriel Hissler Prof. Régis Réau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11340-11356
Conjugated systems based on phospholes and 1,1′‐biphospholes bearing 3,4‐ethylenedithia bridges have been prepared using the Fagan–Nugent route. The mechanism of this organometallic route leading to intermediate zirconacyclopentadienes has been investigated by using theoretical calculations. This study revealed that the oxidative coupling leading to zirconacyclopentadienes is favored over oxidative addition within the S? C≡C bond both thermodynamically and kinetically. The impact of the presence of the S atoms on the optical and electrochemical behavior of the phospholes and 1,1′‐biphospholes has been systematically evaluated both experimentally and theoretically. A comparison with their “all‐carbon” analogues is provided. Of particular interest, this comparative study revealed that the introduction of S atoms has an impact on the electronic properties of phosphole‐based conjugated systems. A decrease of the HOMO–LUMO separation and a stabilization of the LUMO level were observed. These general trends are also observed with 1,1′‐biphospholes exhibiting σ–π conjugation. The P atom of the 3,4‐ethylenedithiaphospholes can be selectively oxidized by S8 or O2. These P modifications result in a lowering of the HOMO–LUMO separation as well as an increase of the reduction and oxidation potentials. The S atoms of the 3,4‐ethylenedithia bridge of the 2,5‐phosphole have been oxidized using m‐chloroperoxybenzoic acid. The resulting 3,4‐ethylenesulfoxide oxophosphole was characterized by an X‐ray diffraction study. Experimental and theoretical studies show that this novel chemical manipulation results in an increase of the HOMO–LUMO separation and an important decrease of the LUMO level. The electropolymerization of 2‐thienyl‐capped 3,4‐ethylenedithiathioxophosphole and 1,1′‐biphosphole is reported. The impact of the S substituents on the polymer properties is discussed. 相似文献
16.
Kirill Popov Tatyana Volovnenko Yulian Volovenko 《Journal of heterocyclic chemistry》2013,50(Z1):E217-E220
A simple, efficient, and clean protocol for the formylation of 2,3‐dihydro‐4H‐1,4‐benzo[e][1,4]thiazin‐3‐on‐1,1‐dioxide is developed. Novel benzothiazine derivatives are synthesized by the reactions of aminovinyl derivative 6 and carbaldehyde 7 with nucleophiles. 相似文献
17.
Single‐Electron Transmetalation: Synthesis of 1,1‐Diaryl‐2,2,2‐trifluoroethanes by Photoredox/Nickel Dual Catalytic Cross‐Coupling 下载免费PDF全文
Dr. DaWeon Ryu David N. Primer John C. Tellis Prof. Dr. Gary A. Molander 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):120-123
Novel methods for the incorporation of fluorinated subunits into organic frameworks are important in pharmaceutical, agrochemical, and materials science applications. Herein, the first method for the cross‐coupling of benzylic α‐trifluoromethylated alkylboron reagents with (hetero)aryl bromides is achieved through application of a photoredox/nickel dual catalytic system. The harsh conditions and high temperatures required by conventional Suzuki‐coupling protocols are avoided by exploitation of an odd‐electron pathway that permits room temperature transmetalation of these recalcitrant reagents. This method represents the first direct and general route for the synthesis of unsymmetrical 1,1‐diaryl‐2,2,2‐trifluoroethanes, thereby providing efficient access to a previously unexplored chemical space. 相似文献
18.
Germacyclobutenes: Generation by 1,1‐Carbalumination or 1,1‐Carbagallation and Their Photophysical Properties 下载免费PDF全文
Prof. Dr. Werner Uhl Stefan Pelties Jens Tannert Prof. Dr. Bart Jan Ravoo Prof. Dr. Ernst‐Ulrich Würthwein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2629-2637
Aluminium‐ and gallium‐functionalised alkenylalkynylgermanes, R12Ge(C?C?R2)[C{E(CMe3)2}?C(H)?R2] (E=Al, Ga), exhibit a close contact between the coordinatively unsaturated Al or Ga atoms and the α‐C atoms of the intact ethynyl groups. These interactions activate the Ge?C(alkynyl) bonds and favour the thermally induced insertion of these C atoms into the E?C(vinyl) bonds by means of 1,1‐carbalumination or 1,1‐carbagallation reactions. For the first time the latter method was shown to be a powerful alternative to known metallation processes. Germacyclobutenes with an unsaturated GeC3 heterocycle and endo‐ and exocyclic C?C bonds resulted from concomitant Ge?C bond formation to the β‐C atoms of the alkynyl groups. These heterocyclic compounds show an interesting photoluminescence behaviour with Stokes shifts of >110 nm. The fascinating properties are based on extended π‐delocalisation including σ*‐orbitals localised at Ge and Al. High‐level quantum chemical DFT and TD‐DFT calculations for an Al compound were applied to elucidate their absorption and emission properties. They revealed a biradical excited state with the transfer of a π‐electron into the empty p‐orbital at Al and a pyramidalisation of the metal atom. 相似文献
19.
A series of 6′‐chloro‐1′,1′‐dioxo‐2′H‐spiro[benzo[d][1,3,7]oxadiazocine‐4,3′‐(1,4,2‐benzodithiazine)]‐2,6(1H,5H)‐dione derivatives 2a , 2b and 3a , 3b have been synthesized starting from 3‐aminobenzodithiazines 1a , 1b and isatoic anhydride. Subsequent reactions of 2a with 3‐chlorophenyl isocyanate gave condensation products 4 and 5 . Compound 2a was also converted into 3‐(2‐aminobenzamido)‐6‐chloro‐7‐methyl‐1,1‐dioxo‐1,4,2‐benzodithiazine derivatives 6 , 7 , 8 , 9 , 10 . The mechanisms of the reactions are discussed. 相似文献
20.
Roger Welti Yvonne Abel Volker Gramlich Franois Diederich 《Helvetica chimica acta》2003,86(3):548-562
This paper describes the development of novel aromatic platforms for supramolecular construction. By the Suzuki cross‐coupling protocol, a variety of functionalized m‐terphenyl derivatives were prepared (Schemes 1–4). Macrolactamization of bis(ammonium salt) (S,S)‐ 6 with bis(acyl halide) 7 afforded the macrocyclic receptor (S,S)‐ 2 (Scheme 1), which was shown by 1H‐NMR titration studies to form ‘nesting' complexes of moderate stability (Ka between 130 and 290 M ?1, 300 K) with octyl glucosides 13 – 15 (Fig. 2) in the noncompetitive solvent CDCl3. Suzuki cross‐coupling starting from 3,3′,5,5′‐tetrabromo‐1,1′‐biphenyl provided access to a novel series of extended aromatic platforms (Scheme 5) for cleft‐type (Fig. 1) and macrotricyclic receptors such as (S,S,S,S)‐ 1 . Although mass‐spectral evidence for the formation of (S,S,S,S)‐ 1 by macrolactamization between the two functionalized 3,3′,5,5′‐tetraaryl‐1,1′‐biphenyl derivatives (S,S)‐ 33 and 36 was obtained, the 1H‐ and 13C‐NMR spectra of purified material remained rather inconclusive with respect to both purity and constitution. The versatile access to the novel, differentially functionalized 3,3′,5,5′‐tetrabromo‐1,1′‐biphenyl platforms should ensure their wide use in future supramolecular construction. 相似文献