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1.
Miao Zhan Hongxia Jiang Xuehai Pang Tao Zhang Ruixue Xu Lifeng Zhao Yu Liu Yu Gong Yuanwei Chen 《Tetrahedron letters》2014
A highly effective and operationally practical method for the regioselective deuteration of N-alkyl-substituted anilines employing Ru3(CO)12 (?1 mol %) as catalyst and D2O as deuterium source was described. A variety of N-alkyl-substituted anilines were efficiently deuterated (up to 98%) at the ortho and/or para position with respect to the nitrogen at neutral conditions. Under the present conditions, deuterated anilines can be easily obtained with simple extraction and evaporation. Substituents with aromatic methoxy groups would not influence the selectivity compared to previous method. 相似文献
2.
An efficient total synthesis of rhein and diacerhein has been accomplished by relying on a remarkable regioselective directed ortho metalation (DOM) followed by a one-pot two step addition-cyclization reaction, generating phthalide 5 intermediate efficiently. 相似文献
3.
Guillaume Viault Jean-Jacques Helesbeux Pascal Richomme Denis Séraphin 《Tetrahedron letters》2018,59(27):2627-2630
A regioselective method for the semisynthesis of phenazine derivatives has been disclosed through an efficient IBX mediated ortho-quinone formation from vitamin E derivatives. High chemo- and regio-selectivity was observed during the oxidation step and the corresponding 5,6-ortho-quinones could react with various phenylenediamines. Thus, this methodology proves its interest as a concise semisynthetic pathway to phenazine-vitamin E hybrids with moderate to good yields. 相似文献
4.
Ka Young Lee 《Tetrahedron letters》2007,48(11):2007-2011
An expeditious synthetic method of 3-arylidenelactams was developed starting from N-tosylaziridines, which were made from the reaction of N-tosylimines and cinnamyl bromides by using the sulfur ylide chemistry. The regioselective ring-opening reaction of N-tosylaziridines with anilines, as external nucleophiles, and the following lactamization afforded 3-arylidenelactams. In the absence of external nucleophiles, intramolecular lactonization occurred to afford 3-arylidenelactones. 相似文献
5.
A highly regioselective ortho-acetoxylation of N-(2-benzoylphenyl)benzamides has been achieved using a catalytic amount of Pd(OAc)2 (10 mol %) and a stoichiometric amount of PhI(OAc)2 in a mixture of acetic anhydride and acetic acid via C-H activation to produce the corresponding 2-acetoxybenzamides in good yields. ortho-Methoxylation has been accomplished using methanol under similar conditions. 相似文献
6.
Highly ortho‐Selective Chlorination of Anilines Using a Secondary Ammonium Salt Organocatalyst
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Dr. Xiaodong Xiong Prof. Dr. Ying‐Yeung Yeung 《Angewandte Chemie (International ed. in English)》2016,55(52):16101-16105
An organocatalytic, highly facile, efficient, and regioselective ortho‐chlorination of anilines is described. A secondary ammonium chloride salt has been employed as the catalyst and the reaction can be conducted at room temperature without protection from air and moisture. In addition, the reaction is readily scalable and the catalyst can be recycled and reused. This catalytic protocol has been applied to the efficient synthesis of a highly potent c‐Met kinase inhibitor. Mechanistic studies revealed that unique structural features of the secondary ammonium chloride salt are important for both the catalysis and regioselectivity of the electrophilic ortho‐chlorination. 相似文献
7.
A new and efficient method for the preparation of ortho-N-Boc-arylmethyl ketone derivatives is reported. The reaction involves the intermediacy of a 4-methylene-3,1-benzoaxin-2-one moiety which smoothly converts to the target compounds under acidic conditions. The ortho-N-Boc-arylmethyl ketone derivatives can be formed in a one-pot reaction or alternatively the 4-methylene-3,1-benzoaxin-2-ones can be isolated and subsequently transformed into the desired products. 相似文献
8.
An efficient protocol was developed for regio-selective Pd-catalyzed direct ortho-fluorination of 2-arylbenzo[d]thiazoles using N-fluorobenzenesulfonimide (NFSI) as the F+ source, and l-proline as the crucial promoter. The present method offered a practical route to synthesize valuable fluorinated products, which are of potential importance in the pharmaceutical and agrochemical industries. 相似文献
9.
Hitesh B. JalaniAmit N. Pandya Dhaivat H. PandyaJayesh A. Sharma V. SudarsanamKamala K. Vasu 《Tetrahedron letters》2012,53(32):4062-4064
Herein, we report an efficient, greener, and solvent-free novel method for the synthesis of 3-substituted quinazolin-4(3H)ones and thienopyrimidin-4(3H)ones in a one-pot sequence using methyl anthranilate or 2-aminothiophene-3-carboxylate with N,N′-dimethyl formamide dimethyl acetal and various anilines. The driving force for this reaction is the removal of N,N′-dimethylamine by various anilines resulting in 3-substituted quinazolin-4(3H)ones and thienopyrimidin-4(3H)ones. 相似文献
10.
Nasser Iranpoor Habib Firouzabadi Dariush Khalili Rezvan Shahin 《Tetrahedron letters》2010,51(27):3508-1435
Highly regioselective thiocyanations of indoles, anilines and pyrrole are achieved via an efficient and simple protocol using NH4SCN and diethyl azodicarboxylate (DEAD) as a mild oxidant. 相似文献
11.
1-Chlorovinyl p-tolyl sulfoxides were synthesized from ketones and chloromethyl p-tolyl sulfoxide in high yields. Treatment of the sulfoxides with isopropylmagnesium chloride at −78 °C in toluene gave magnesium alkylidene carbenoids (α-chloro alkenylmagnesium chlorides), which were treated with N-lithio arylamines to afford ortho-alkenylated arylamines in moderate yields. The reaction, in some cases, proceeded in a highly stereospecific manner at the carbon bearing the chlorine and the sulfinyl group. The structures of the α-chloro alkenylmagnesium chlorides and the reactivity of the N-lithio meta-substituted anilines were studied at the B3LYP and MP2 levels of theory with the 6-31(+)G* basis set. This reaction offers a quite novel and direct alkenylation of arylamines at the ortho-position of the aromatic ring. 相似文献
12.
James C. HaberMichael A. Lynch Stacey L. SpringAnthony D. Pechulis Joseph RakerYi Wang 《Tetrahedron letters》2011,52(44):5847-5850
An efficient, mild and transition-metal-free method for the N-arylation of acetanilides, leading to a range of unsymmetrical diarylamine products is reported. Reactions of ortho-silylaryl triflates with acetanilides in the presence of tetrabutylammonium triphenyldifluorosilicate (TBAT) in toluene afforded the desired products in good to excellent yields. Regioselectivity was also observed when unsymmetrical aryne precursors were used. 相似文献
13.
Kazuteru Umetsu 《Tetrahedron letters》2008,49(17):2722-2725
Thermal double cyclization reaction using ortho-vinylbenzaldehyde and 3-aminopropanols proceeded smoothly to give isoquinoline derivatives via 6π-azaelectrocyclization pathway. The method was applied to the efficient synthesis of (S)-cryptostyline II. 相似文献
14.
An efficient regioselective, catalyst free, and green protocol has been developed for the synthesis of a novel class of 4H-chromene scaffolds at room temperature in ionic liquid. The method is general and applicable for a series of 2H-chromenes as well as indole derivatives. 相似文献
15.
Highly regioselective copper catalyzed ortho-chlorination of aryl pyridines was achieved with TBHP as oxidant and 1,2-dichloroethane as chlorinating agent for the first time. Switching the oxidant from TBHP to benzoyl peroxide under identical reaction conditions effects ortho-oxygenation. 相似文献
16.
Thomas Cailly 《Tetrahedron letters》2005,46(1):135-137
Ortholithiation of 4-cyanopyridine using 2,2,6,6-tetramethylpiperidide (LiTMP) and trapping the lithio intermediate with electrophiles represents an efficient and straightforward access to ortho-substituted-4-cyanopyridines. The cyano group can be used as an ortho-directing group and allows the preparation of 3-halogeno-4-cyanopyridines. Reactivity of 2- and 3-cyanopyridines is also investigated and seems to give similar results. 相似文献
17.
Katarzyna B?a?ewskaTadeusz Gajda 《Tetrahedron》2003,59(51):10249-10254
Easily available N-(diethoxyphosphoryl)-O-benzylhydroxylamine was shown to be convenient, orthogonally protected substrate for regioselective N-alkylation by means of diverse halides under basic conditions (sodium hydride/tetrabutylammonium bromide). An efficient procedure for dephosphorylation of N-substituted N-(diethoxyphosphoryl)-O-benzylhydroxylamine to provide N-substituted O-benzylhydroxylamines was also established. 相似文献
18.
Maria Grazia CabidduSalvatore Cabiddu Enzo CadoniStefania De Montis Claudia FattuoniStefana Melis 《Tetrahedron》2003,59(16):2893-2897
The metallation reaction of N-Boc-and N-Piv-(methylthio)anilines are here described. The results show that N-Boc derivatives are metallated only by superbases to give products substituted at the thiomethylic group. N-Piv derivatives show a different behaviour: ortho-derivative is metallated by both butyllithium and superbase at the thiomethylic carbon atom, while para-derivative is metallated in ortho to the N-Piv group by butyllithium and at the thiomethylic carbon atom by superbase. The meta-derivative is metallated only by superbase at the thiomethylic carbon atom. 相似文献
19.
David J. Michaelis 《Tetrahedron letters》2009,50(17):1920-431
Stabilized ortho-bromo phenyllithium reagents, generated via lithium-halogen exchange of aryl iodides, undergo regioselective ring opening of mono-substituted N-Boc, N-Cbz, and N-tosyl-protected aziridines in good to excellent yields. The resulting ortho-bromo phenethylamines can be cyclized under transition-metal-catalyzed conditions to give 2-substituted chiral, non-racemic indolines in good yields. 相似文献
20.
Tadej Stropnik 《Tetrahedron letters》2008,49(11):1729-1733
A regioselective method for the bromination of phenols, ethers and anilines using a ZrBr4/diazene mixture is described. The reaction takes place under mild reaction conditions and the bromine atom adds first at the para unsubstituted position with respect to the OH, OR or NR2 group of the activated aromatic substrate. Less reactive compounds such as toluene, phenyl acetate, benzonitrile and trifluoromethylbenzene remain intact under the same conditions. 相似文献