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1.
The reactions of bis(trimethylstannyl)ethyne, Me3Sn–C?C–SnMe3 ( 4 ), with trimethylsilyl‐ or dimethylsilyl‐dialkylboryl‐substituted alkenes 1 – 3 afford organometallic‐substituted allenes 5 , 6 and 8 , 9 in high yield. In the case of (E)‐2‐trimethylsilyl‐3‐diethylboryl‐2‐pentene ( 1) , a butadiene derivative 7 could be detected as an intermediate prior to rearrangement into the allene. All reactions were monitored by 29Si and 119Sn NMR, and the products were characterized by an extensive NMR data set (1H, 11B, 13C, 29Si, 119Sn NMR). Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
The reaction of tetra(alkyn‐1‐yl)silanes Si(C?C‐R1)4 1 [R1 = tBu ( a ), Ph ( b ), C6H4‐4‐Me ( c )] with 9‐borabicyclo[3.3.1]nonane (9‐BBN) in a 1:2 ratio affords the spirosilane derivatives 5a – c as a result of twofold intermolecular 1,2‐hydroboration, followed by twofold intramolecular 1,1‐organoboration. Intermediates 3a–c , in which two alkenyl‐ and two alkyn‐1‐yl groups are linked to silicon, were identified by NMR spectroscopy. The molecular structure of the spiro compound 5c was determined by X‐ray analysis, and the solution‐state structures of products and intermediates follow conclusively from the consistent NMR spectroscopic data sets (1H, 11B, 13C and 29Si NMR). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
1-Boraadamantane 1 was treated with alkyn-1-ylsilanes 2 containing one or two Si[bond]H functions. Under mild conditions, the reaction gave 4-methylene-3-borahomoadamantane derivatives 4 quantitatively and selectively by 1,1-organoboration. An electron deficient Si-H-B bridge was present in the product. The analogous reaction of 1 with an alkyn-1-yl-disilane 3 gave the corresponding alkene derivative 5, however, without the Si-H-B bridge. Evidence for the Si-H-B bridge in 4 was given by IR data, an extensive set of NMR spectroscopical data ((1)H, (11)B, (13)C, (29)Si NMR) including various unusual isotope effects on chemical shifts and coupling constants, as well as from the molecular structure of one example, 4 e, in the solid state. The precursor of 4 e, alkyne 2 e, Ph(2)Si(H)C[triple bond]CSi(H)Ph(2), was also studied by X-ray analysis. 相似文献
4.
The reactions of alkyn‐1‐yl(vinyl)silanes R2Si[C?C‐Si(H)Me2]CH?CH2 [R = Me (1a), Ph (1b)], Me2Si[C?C‐Si(Br)Me2]CH?CH2 (2a), and of alkyn‐1‐yl(allyl)silanes R2Si[C?C‐Si(H)Me2]CH2CH?CH2 (R = Me (3a), R = Ph (3b)] with 9‐borabicyclo[3.3.1]nonane in a 1:1 ratio afford in high yield the 1‐silacyclopent‐2‐ene derivatives 4a, b and 5a, and the 1‐silacyclohex‐2‐ene derivatives 6a, b, respectively, all of which bear a functionally substituted silyl group in 2‐position and the boryl group in 3‐position. This is the result of selective intermolecular 1,2‐hydroboration of the vinyl or allyl group, followed by intramolecular 1,1‐organoboration of the alkynyl group. In the cases of 4a, b, potential electron‐deficient Si? H? B bridges are absent or extremely weak, whereas in 6a,b the existence of Si? H? B bridges is evident from the NMR spectroscopic data (1H, 11B, 13C and 29Si NMR). The molecular structure of 4b was determined by X‐ray analysis. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
5.
6.
The reaction of bis(silyl)ethynes 2 – 4 , bearing one, two and three hydrides at one of the silicon atoms, with triallylborane 1 leads primarily to alkenes 5 , 8 and 11 respectively by 1,1‐allylboration. In these alkenes, the diallylboryl and the silyl group bearing one or more Si? H functions are in cis‐positions at the C?C bond, giving rise to the formation of an electron‐deficient Si? H? B bridge. This follows unambiguously from the consistent set of NMR data, in particular from the observation of isotope‐induced chemical shifts 2Δ10/11B(29Si). The activation of the Si? H bond in 5 , 8 and 11 induces intramolecular hydrosilylation under very mild reaction conditions to give 1,4‐silabora‐cyclo‐2‐heptenes 7 , 10 and 13 respectively. Upon heating, these seven‐membered heterocycles undergo ring contraction by 1,1‐deallylboration to give the 1‐sila‐cyclo‐2‐hexenes 14 – 16 , and bear an exocyclic diallylboryl group in 3‐position. All proposed structures are based on consistent 1H, 11B, 13C and 29SiNMR data. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
7.
The reaction of alkyn‐1‐yl(chloro)(methyl)vinyl‐ and alkyn‐1‐yl(chloro)(phenyl)‐vinylsilane with 9‐borabicyclo[3.3.1]nonane (9‐BBN) afforded selectively 1‐silacyclopent‐2‐ene derivatives containing a Si? Cl function, as a result of consecutive 1,2‐hydroboration and 1,1‐organoboration. Protodeborylation with acetic acid left the Si? Cl functions in various 1‐silacyclopent‐2‐enes untouched, whereas acetic acid in the presence of dipropylamine led to conversion of the Si? Cl into the Si? OAc function. New starting materials and all products were characterized in solution by multinuclear NMR spectroscopy (1H, 11B, 13C and 29Si NMR), and the molecular structures of two 1‐silacyclopent‐2‐ene derivatives were determined by X‐ray analysis. The gas phase geometries of 1‐silacyclopent‐2‐enes were optimized by DFT calculations [B3LYP/6‐311 + G(d,p) level of theory], found to be in reasonable agreement with the results of the crystal structure determination, and NMR parameters were calculated at the same level of theory. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
1,1‐Dibromo‐2,2‐bis(trimethylsilylethynyl)ethene ( 2 ) reacts with two equivalents of 1‐boraadamantane ( 1 ) by 1,1‐organoboration of both trimethylsilylethynyl groups to give a triene 3 bearing two 4‐methylene‐3‐borahomoadamantane moieties in terminal positions. The triene was characterized by one‐ and two‐dimensional 1H, 11B, 13C and 29Si NMR spectroscopy in solution and X‐ray structural analysis in the solid state. The planes of the C double bond are strongly twisted against each other as a result of the bulky substituents, and the surroundings of the boron atoms deviate from the ideal trigonal planar geometry owing to the tension in the tricyclic frameworks. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
9.
1,1‐Organoboration, using triethyl‐, triallyl‐ and triphenyl‐borane (BEt3, BAll3, BPh3), of dimethysilylethynyl(trimethyl)stannane, Me3Sn? C?C? Si(H)Me2 ( 1 ), affords alkenes bearing three different organometallic groups at the C?C bond. For BEt3 and BPh3, the first products are the alkenes 4 with boryl and stannyl groups in cis‐positions. These rearrange by consecutive 1,1‐deorganoboration and 1,1‐organoboration into the isomers 5 as the final products, where boryl and silyl groups are in cis‐positions linked by an electron‐deficient Si? H? B bridge. 1,1‐Ethylboration of bis(dimethylsilylethynyl)dimethylstannane, Me2Sn[C?C? Si(H)Me2]2 ( 2 ), leads to the stannacyclopentadiene 6 along with non‐cyclic di(alkenyl)tin compounds 7 and 8 . 1,1‐Ethylboration of ethynyl(trimethylstannylethynyl)methylsilane, Me(H)Si(C?C? SnMe3)C?C? H ( 3 ), leads selectively to a new silacyclopentadiene 13 as the final product. The reactions were monitored and the products were characterized by multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 29Si and 119Sn NMR). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
10.
The reaction of 1‐silyl‐1‐borylalkenes with alkyn‐1‐yltin compounds affords borol‐2‐enes, organometallic‐substituted allenes, mixtures thereof or even more complex mixtures with buta‐1,3‐dienes, depending on the third substituent at the C?C bond (Bu or Ph), on the number of Si? Cl functions (two or three) and the nature of the alkyn‐1‐yltin compound. Six new borol‐2‐enes were isolated in pure state, and two of them were characterized by X‐ray structural analysis. The solution‐state structures of all major products were clearly established by multinuclear magnetic resonance methods (1H, 11B, 13C, 29Si, 119Sn NMR). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
11.
The 1,2‐hydroboration of the chloro(hexyn‐1‐yl)‐ ( 1a ) and chloro(phenylethyn‐1‐yl)diphenylsilanes ( 1b ) with 9‐borabicyclo[3.3.1]nonane afforded selectively the alkenylsilanes 2a, b , in which the boryl and the silyl groups are linked to the same olefinic carbon atom. In case of 2a , treatment with phenylethynyl lithium gave a mixture of the alkyn‐1‐ylborate 3a and the alkenyl(phenylethynyl)diphenylsilanes 4a . In the case of 2b , only the alkyn‐1‐ylsilane 4b was identified as an intermediate. Both 4a, b slowly rearranged by intramolecular 1,1‐vinylboration into the silacyclobutenes 5a, b . The intermediates were characterized by 1H, 11B, 13C and 29Si NMR spectroscopy in solution, and the molecular structure of the 1‐silacyclobutene 5a was determined by X‐ray analysis. The gas phase geometries of model molecules corresponding to 5a were optimized by MO calculations using DFT methods [B3LYP/6‐311 + G(d,p) level of theory], found to be in reasonable agreement with the results of the crystal structure determination, and NMR parameters were calculated at the same level of theory. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
Copper‐Mediated Aromatic 1,1‐Difluoroethylation with (1,1‐Difluoroethyl)trimethylsilane (TMSCF2CH3)
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Xinjin Li Dr. Jingwei Zhao Yunze Wang Jian Rong Dr. Mingyou Hu Dr. Dingben Chen Pan Xiao Dr. Chuanfa Ni Prof. Dr. Limin Wang Prof. Dr. Jinbo Hu 《化学:亚洲杂志》2016,11(12):1789-1792
A new method for the formation of 1,1‐difluoroethyl copper species (“CuCF2CH3”) with 1,1‐difluoroethylsilane (TMSCF2CH3) has been developed. The “CuCF2CH3” species can be applied to the efficient 1,1‐difluoroethylation of diaryliodonium salts under mild conditions, affording (1,1‐difluoroethyl)arenes in good to excellent yields. This convenient procedure tolerates a wide range of functional groups and thus serves as a practical synthetic tool for the introduction of CF2CH3 group(s) into complex molecules. 相似文献
13.
The reactions of diethylaminoethynyl(trimethyl)silane (1), bis(diethylaminoethynyl)methylsilane (2), diethylaminoethynyl(trimethyl)germane (3), dimethylaminoethynyl(triethyl)germane (4), diethylaminoethynyl(trimethyl)stannane (5) and methyl(phenyl)aminoethynyl(trimethyl)stannane (6) with trialkylboranes [BEt3 (7b), BPr3 (7c), BiPr3 (7d) and 9‐alkyl‐9‐borabicyclo[3.3.1]nonanes 9‐Me‐9‐BBN (8a) and 9‐Et‐9‐BBN (8b)] were studied. The alkynes 1 and 2 did not react even with boiling BEt3, whereas the reactions of 3–6 afforded mainly novel enamines [(E)‐1‐amino‐1‐trialkylgermyl‐2‐dialkylboryl‐alkenes (9, 10), (E)‐1‐diethylamino‐1‐trimethylstannyl‐2‐dialkylboryl‐alkenes (11, 12), (E)‐1‐methyl(phenyl)amino‐1‐trimethylstannyl‐2‐dialkylboryl‐alkenes (13, 14)]. This particular stereochemistry is unusual for products from 1,1‐organoboration reactions, indicating a special influence of the amino group. The starting materials and products were characterized by multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 15N, 29Si, 119Sn NMR). Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
14.
Qiaoyi Wang Stephen E. Motika Dr. Novruz G. Akhmedov Prof. Jeffrey L. Petersen Prof. Xiaodong Shi 《Angewandte Chemie (International ed. in English)》2014,53(21):5418-5422
The first catalytic alkyne hydroboration of propargyl amine boranecarbonitriles is accomplished with triazole‐AuI complexes. While the typical [L‐Au]+ species decomposes within minutes upon addition of amine boranecarbonitriles, the triazole‐modified gold catalysts (TA‐Au) remained active, and allowed the synthesis of 1,2‐BN‐cyclopentenes in one step with good to excellent yields. With good substrate tolerability and mild reaction conditions (open‐flask), this new method provides an alternative route to reach the interesting cyclic amine borane with high efficiency. 相似文献
15.
Zhaoyang Cheng Shipei Xing Jun Guo Biao Cheng Lan‐Fang Hu Xing‐Hong Zhang Zhan Lu 《中国化学》2019,37(5):457-461
A regioselective double 1,1‐hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem‐Bis(dihydrosilyl)alkanes containing four silicon‐hydrogen bonds are efficiently constructed in an atom‐economical manner. Tolerated substrates include simplest alkyne‐ethyne, a complicated drug derivative and various functionalized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excellent enantioselectivities to access corresponding chiral products. The transformations of Si—H bonds into Si—C, Si—O, and Si—F bonds and the synthesis of enantioriched α‐hydroxysilane show synthetic utility. 相似文献
16.
Simon Steinhauer Dr. Julia Bader Dr. Hans‐Georg Stammler Dr. Nikolai Ignat‘ev Prof. Dr. Berthold Hoge 《Angewandte Chemie (International ed. in English)》2014,53(20):5206-5209
The synthesis and complete characterization of functional, highly Lewis acidic tris(pentafluoroethyl)silanes as well as tetrakis(perfluoroalkyl)silanes Si(C2F5)4 and Si(C2F5)3CF3 by direct fluorination is described. The reaction of SiCl4 with LiC2F5 invariably affords (pentafluoroethyl)fluorosilicates. To avoid silicate formation by fluoride transfer from LiC2F5 the Lewis acidity of the silane has to be decreased by electron‐donating substituents, such as dialkylamino groups. The easily accessible Si(C2F5)3NEt2 is a valuable precursor for a series of tris(pentafluoroethyl)silanes. 相似文献
17.
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
18.
Laura Ascherl Camilla Evangelisti Prof. Dr. Thomas M. Klapötke Dr. Burkhard Krumm Julia Nafe Anian Nieder Sebastian Rest Christian Schütz Dr. Muhamed Suceska Matthias Trunk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9198-9210
An investigation of the structures and chemistry of substituted hexamethyl disiloxanes ((XCH2)3Si)2O; X=F, Cl, Br, I, N3, and ONO2) is reported. New synthetic routes to the precursor hexakis(chloromethyl)disiloxane are presented. The products with X=Cl, Br, I, and N3 were characterized by NMR, IR, and Raman spectroscopy. In addition, the single‐crystal structures of the products with X=Cl, Br, and I are discussed in detail. The compounds with X=F and ONO2 were not obtained in their pure form; instead investigations of the decomposition products revealed their conversion into intermediates. Theoretical calculations of the gas‐phase structures at the B3LYP/cc‐pVDZ, B3LYP/3‐21G, MP2/6‐31G*, and MP2/3‐21G levels of theory are used to explain the chemical and physical behavior of the compounds with X=Cl, Br, I, N3, and ONO2. A new decomposition pathway of hexakis(nitratomethyl)disiloxane is presented and is used to explain their remarkable instability. The energetic properties and values of the nitrate and azide derivatives were calculated at the CBS‐4M level of theory by using the improved EXPLO5 computer code version 6.01. 相似文献
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20.
Synthesis of Cyclic Alkenylsiloxanes by Semihydrogenation: A Stereospecific Route to (Z)‐Alkenyl Polyenes
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Bryony L. Elbert Diane S. W. Lim Haraldur G. Gudmundsson Jack A. O'Hanlon Dr. Edward A. Anderson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8594-8598
Cyclic alkenylsiloxanes were synthesized by semihydrogenation of alkynylsilanes—a reaction previously plagued by poor stereoselectivity. The silanes, which can be synthesized on multigram scale, undergo Hiyama–Denmark coupling to give (Z)‐alkenyl polyene motifs found in bioactive natural products. The ring size of the silane is crucial: five‐membered cyclic siloxanes also couple under fluoride‐free conditions, whilst their six‐membered homologues do not, enabling orthogonality within this structural motif. 相似文献