共查询到20条相似文献,搜索用时 15 毫秒
1.
A catalytic amount of KF.18-crown-6 complex is effective as a soluble fluoride source to activate an asymmetric Sakurai-Hosomi allylation with BINAP and silver(I) triflate catalyst. The allylation of a variety of aromatic, alpha,beta-unsaturated and aliphatic aldehydes with allylic trimethoxysilane resulted in high yields and remarkable enantioselectivities. In addition, the asymmetric Mukaiyama-type aldol reaction is achieved by using trimethoxysilyl enol ethers in the presence of the same catalysts. High anti selectivity is obtained from E-silyl enol ether, while Z-silyl enol ether gives syn selectivity. 相似文献
2.
Silyl-substituted 1,3-butadienes are useful building blocks and are readily applied in several types of reactions such as Diels-Alder reaction, ene reaction and allylation. They can also participate in different tandem reactions such as Diels-Alder/allylation, ene/allylation, ene/allylation/Diels-Alder reaction, ene/allylation/ene reaction and ene/allylation/Diels-Alder/allylation reaction. This feature article reviews the synthesis of silyl-substituted 1,3-butadienes, and their applications in the reaction types mentioned above, involving a tandem Diels-Alder/ene/allylation process. This article also introduces some reactions of alkenylsilanes and allylsilanes for comparison and discussion about the tandem reaction. The tandem reactions described in this article are a powerful tool to construct complicated multicyclic compounds with high selectivity and high efficiency. 相似文献
3.
A continued study of the recently discovered diazotizative allylation (DiazAll) reaction of aniline derivatives is reported. Several allyl reagents, commonly used in radical allylation reactions, were evaluated, and some of these reagents resulted in allylation when used in the DiazAll reaction. The best result was obtained with allyl bromide. Substituted allylic bromides gave the corresponding allyl aromatic compounds in poor to excellent yields. In comparison with an established method for aromatic allylation, the DiazAll reaction performed well and was superior when a more complex allylic bromide was used. Finally, a new allylation-bromocyclization reaction was demonstrated and used in the synthesis of a known inhibitor of phenylethanolamine N-methyltransferase (PNMT), an enzyme involved in the biosynthesis of adrenaline. 相似文献
4.
The allylation of aromatic amines with alkynes proceeded smoothly in the presence of catalytic amounts of Pd(PPh(3))(4) and benzoic acid. The allylation products were obtained in high yields in a regio- and stereoselective manner. The effect of various groups on the nitrogen atom of anilines was studied. Regardless of the substituent (electron withdrawing or electron donating) on the aromatic ring, the reaction proceeded well. Various functionalities, including -CH(3), -OMe, -Cl, -CN, -COOMe, -NO(2) and -COCH(3) were tolerated under the reaction conditions. Similarly, the allylation of alpha-aryl aldehydes proceeded well with the same level of regio- and stereoselectivity as the allylation of aromatic amines. This reaction provides the second example of the transition metal catalyzed direct alpha-allylation of aldehydes. 相似文献
5.
6.
Phosphine oxides were found to be efficient neutral coordinate-organocatalysts (NCOs) for the allylation of N-acylhydrazones. Among the phosphine oxides tested, a three carbon-tethered bisphosphine oxide (dppp dioxide) was found to be the most effective, and in the presence of dppp dioxide, less reactive aromatic and [small alpha],[small beta]-unsaturated N-acylhydrazones underwent allylation as well as diastereoselective crotylation. Furthermore, a polymer-supported phosphine oxide was also developed as an effective immobilized NCO. 相似文献
7.
Naka H Uchiyama M Matsumoto Y Wheatley AE McPartlin M Morey JV Kondo Y 《Journal of the American Chemical Society》2007,129(7):1921-1930
An aluminum ate base, i-Bu(3)Al(TMP)Li, has been designed and developed for regio- and chemoselective direct generation of functionalized aromatic aluminum compounds. Direct alumination followed by electrophilic trapping with I(2), Cu/Pd-catalyzed C-C bond formation, or direct oxidation with molecular O(2) proved to be a powerful tool for the preparation of 1,2- or 1,2,3-multisubstituted aromatic compounds. This deprotonative alumination using i-Bu3Al(TMP)Li was found to be effective in aliphatic chemistry as well, enabling regio- and chemoselective addition of functionalized allylic ethers and carbamates to aliphatic and aromatic aldehydes. A combined multinuclear NMR spectroscopy, X-ray crystallography, and theoretical study showed that the aluminum ate base is a Li/Al bimetallic complex bridged by the nitrogen atom of TMP and the alpha-carbon of an i-Bu ligand and that the Li exclusively serves as a recognition point for electronegative functional groups or coordinative solvents. The mechanism of directed ortho alumination reaction of functionalized aromatic compounds has been studied by NMR and in situ FT-IR spectroscopy, X-ray analysis, and DFT calculation. It has been found that the reaction proceeds with facile formation of an initial adduct of the base and aromatic, followed by deprotonative formation of the functionalized aromatic aluminum compound. Deprotonation by the TMP ligand rather than the isobutyl ligand was suggested and reasoned by means of spectroscopic and theoretical study. The remarkable regioselectivity of the ortho alumination reaction was explained by a coordinative approximation effect between the functional groups and the counter Li(+) ion, enabling stable initial complex formation and creation of a less strained transition state structure. 相似文献
8.
Catalytic enantioselective allylation of aldehydes via a chiral indium(III) complex in ionic liquids
The ionic liquid [hmim][PF6] has been demonstrated as an efficient and environmentally-friendly reaction medium for the enantioselective allylation of aldehydes via a chiral indium(III) complex. The allylation of a variety of aromatic, α,β-unsaturated and aliphatic aldehydes resulted in moderate to good yields and enantioselectivities (upto 92% ee). 相似文献
9.
Barbier-type reaction mediated with tin nano-particles in water 总被引:1,自引:0,他引:1
Tin nano-particles are employed in the Barbier-type allylation reaction of carbonyl compounds in water to afford the corresponding homoallylic alcohols in good yields. The in situ generated allylation intermediates, allyltin(II) bromide and diallyltin dibromide, have been directly observed by using 1H NMR. A mechanism is proposed based on this observation. 相似文献
10.
Treatment of a mixture of aromatic compound and ethyl α-(methylsulfinyl)acetate (5) with p-toluenesulfonic acid under continuous removal of separated water brought about an intermolecular aromatic substitution to give ethyl α-(methylthio)arylacetate (6). Similar treatment of acylmethyl phenethyl sulfoxide (8) led to cyclization into 1-acylisothiochroman (9). 相似文献
11.
Jacques Augé Nadège Lubin-Germain Sylvain Marque Latifa Seghrouchni 《Journal of organometallic chemistry》2003,679(1):79-83
Barbier allylation reaction of carbonyl compounds with allyl bromide was investigated using a catalytic amount of indium (0), indium (I) or indium (III) salts in the presence of a reducer and chlorotrimethylsilane (TMSCl). The Mn/TMSCl couple turned out to be the most efficient system to regenerate active indium in the allylation reaction of various carbonyl compounds including α- and β-oxygenated aldehydes. 相似文献
12.
[reaction: see text] New axially chiral 2,2'-bipyridine N,N'-dioxides were obtained by a new method that does not involve any procedures for the separation of enantiomers. One of the dioxides, (R)-3,3'-bis(hydroxymethyl)-6,6'-diphenyl-2,2'-bipyridine N,N'-dioxide, exhibited extremely high catalytic activity for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The allylation of aromatic aldehydes proceeded in the presence of 0.01 or 0.1 mol % of the dioxide catalyst to give the corresponding homoallyl alcohols of up to 98% ee. 相似文献
13.
Pignataro L Benaglia M Annunziata R Cinquini M Cozzi F 《The Journal of organic chemistry》2006,71(4):1458-1463
A series of structurally simple pyridine N-oxides have readily been assembled from inexpensive amino acids and tested as organocatalysts in the allylation of aldehydes with allyl(trichloro)silane to afford homoallylic alcohols. (S)-proline-based catalysts afforded the products derived from aromatic aldehydes in fair to good yields and in up to 84% enantiomeric excess (ee). The allylation of heteroaromatic, unsaturated, and aliphatic aldehydes was less satisfactory. By running the reaction in the presence of achiral and chiral additives and structurally different catalysts, we collected some insights into the relationship between the stereochemical outcome and the catalyst's structural features. Even if the ee's obtained are inferior to the best values observed with other catalysts, this work concurs to show that structurally simple pyridine N-oxides can also promote the allylation reaction with satisfactory stereocontrol. 相似文献
14.
Kui Wu Lushun Wang Sonivette Coln‐Rodríguez Gerd‐Uwe Flechsig Ting Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1788-1792
The development of visible‐light‐mediated allylation of unactivated sp3 C?H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre‐functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C?H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ‐carbon radical acceptor. 相似文献
15.
An air- and moisture-stable SeCSe-Pd(II) pincer complex was synthesized and found to catalyze the nucleophilic allylation of aldehydes with allyltributyltin. The allylation of a variety of aromatic and aliphatic aldehydes to give the corresponding homoallyl alcohols was performed at room temperature to 60 degrees C in yields ranging from 50% (for typical aliphatic aldehydes) to up to 97% (for aromatic aldehydes) using 5 x 10(-3) to 1 mol % of the Pd catalyst. NMR spectroscopic study indicated that a sigma-allylpalladium intermediate was formed and possibly functions as the nucleophilic species that undergoes addition to the aldehydes. 相似文献
16.
A new and convenient procedure for synthesis of homoallylic alcohols in generally good to excellent yields has been developed. The bismuth-mediated Barbier-type allylation of aldehydes (aromatic, aliphatic, alicyclic and heterocyclic) with allyl bromide has been carried out smoothly in water in the presence of fluoride ions. 相似文献
17.
A chiral indium(III)-PYBOX complex prepared from indium triflate and chiral PYBOX has been discovered to effect high enantioselectivities in the addition of allyltributyl stannane to aldehydes. The allylation of a variety of aromatic, alpha,beta-unsaturated, and aliphatic aldehydes resulted in good yields and high enantioselectivities (up to 94% ee). 相似文献
18.
A catalytic system, Pd(OAc)2 (10 mol %)-P(n-Bu)3 (20 mol %)-Et3B (360 mol %), promotes allylic alcohols to undergo the allylation of anisidine-imines of aromatic and aliphatic aldehydes and furnishes homoallylamines in good to moderate yields. The reaction shows unique stereoselectivity, giving anti-isomers selectively. [reaction: see text] 相似文献
19.
Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones. 相似文献
20.
报道了一个简捷的芳香醛的烯丙基化反应的新体系. 通过使用新型的金属双核烯丙基锡试剂(含有Sn—M键, M=Mn或Fe)与醛在二氯甲烷中反应, 无需使用任何辅助试剂, 直接得到较高产率(42%~98%)的高烯丙基醇. 实验结果证明过渡金属基团及M—Sn键具有相当高的活化锡原子上的烯丙基基团的作用. 相似文献