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1.
Palladium-catalyzed asymmetric ring opening of oxabenzonorbornadienes with readily available organozinc halides under mild conditions in the presence of (S)-Pr(i)-PHOX produces the corresponding 1,2-dihydronaphth-1-ols in good yield and high enantioselectivity. [reaction: see text] 相似文献
2.
An efficient and water tolerant method for the synthesis ofβ-haloamines is described utilizing hydrated nickel(Ⅱ) halides (NiX2ⅩnH2O X = Cl,Br,I) and aziridines as starting materials.N-Tosylaziridines reacted with NiCl2·6H2O or NiI2·6H2O givingβ-chloro -orβ-iodoamines in high yields(73-99%) within a short time,but 10 mol%of n-Bu4NBr should be added in the reactions of N-tosylaziridines with NiBr2·3H2O in order to obtain the high yields of correspondingβ-bromoamines.Solvent played an important role in the reactions.The proper solvent for the reaction of NiCl2·6H2O was DMF,while NiBr2·3H2O or NiI2·6H2O proceeded well in 1,4-dioxane. 相似文献
3.
The complex [PdCl2(P-N)] containing the basic and sterically demanding 8-(di-tert-butylphosphinooxy)quinoline ligand (P-N) is a highly efficient catalyst for the coupling of phenylboronic acid with aryl bromides or aryl chlorides. The influence of solvent and base has been investigated, the highest rates being observed at 110 °C in toluene with K2CO3 as the base. With aryl bromides the reaction rates are almost independent on the electronic properties of the para aryl substituents, on the contrary, reduced reaction rates are observed when bulky substituents are present on the substrate. Nevertheless the coupling of 2-bromo-1,3,5-trimethylbenzene with phenylboronic acid can be carried out to completion in 2 h using a catalyst loading of 0.02 mol %. Under optimized reaction conditions, turnover frequencies as high as 1900 h−1 can be obtained in the coupling of 4-chloroacetophenone with phenylboronic acid; lower reaction rates are obtained with substrates bearing EDG substituents on the aryl group. 相似文献
4.
K.R. Kishore Kumar Reddy 《Tetrahedron letters》2008,49(44):6337-6340
Cyclization of 2-[(4-chloroanilino)methyl]phenol (1) with thiophosphoryl chloride afforded 2-chloro-3-(4-chlorophenyl)-3,4-dihydro-2H-1,3,2λ5-benzoxazaphosphinine-2-thione (2). Reaction of 2 with various heterocyclic amines (3) in the presence of Et3N/NaH gave 3-(4-chlorophenyl)-2-nitrogen heterocyclic substituted-3,4-dihydro-2H-1,3,2λ5-benzoxaza-phosphinine-2-thiones (4). Further reaction of 4 with the N-sodium salt of amino heterocyclics in the presence of HCl at 50-60 °C opened the benzoxazaphosphinine ring chemoselectively at the endocyclic P-O bond and yielded 2-[4-chloro(heterocyclic substituted-phosphorothioyl)anilino]methylphenols 5-13. 相似文献
5.
K.G. Thakur 《Tetrahedron letters》2009,50(24):2865-5152
A wide range of arylated alkynes are synthesized from the corresponding aryl halides and terminal alkynes through Sonogashira type cross-coupling reactions through C(aryl)-C bond formation in the presence of a catalytic amount of N,N′-dibenzyl BINAM-CuI complex under mild reaction conditions. 相似文献
6.
Ruonan Wang Shiwei Wang Dayong Li Feiyang Ye Yuting Leng Yangjie Wu Junbiao Chang Yusheng Wu 《Tetrahedron》2019,75(15):2298-2305
A mild, metal-free and efficient synthesis of 2,3-disubstituted acrylonitriles and α-iminonitriles through radical ring opening reaction of pyridine fused heterocycles has been developed. The tetra-n-butylammonium iodide catalyst acts as a formal one-electron donor. Compared to the previous methods, which require excessive amounts of highly explosive azide sources and the addition of oxidants, this is a safe and convenient transformation. 相似文献
7.
Mohammad Joshaghani Marzieh Daryanavard Ezzat Rafiee Jianliang Xiao 《Tetrahedron letters》2007,48(11):2025-2027
The biphenyl-based phosphine, P(o-C6H4C6H4Me)Ph2, is a moderately bulky and electron-rich phosphine, which has been successfully applied to the palladium catalyzed Suzuki coupling of activated and deactivated aryl halides as well as bromoarylphosphines and bromoarylphosphine oxides, with low catalyst loading and good to excellent conversions and turnovers. 相似文献
8.
Manthan Panchal Anita Kongor Viren Mehta Manoj Vora Keyur Bhatt Vinod Jain 《Journal of Saudi Chemical Society》2018,22(5):558-568
A simple one-pot method is used for the synthesis of water dispersible and stable palladium nanoparticles (PdNps) where oxacalix[4]arene dihydrazide (OXDH) is used as both a reducing and capping agent. The OXDH-PdNps have been characterized by UV–Visible spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDX), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The OXDH-PdNps are spherical in shape with an average size of 3–4?nm and well crystallized in a face centered cubic structure. The capping of the OXDH ligand on the nanoparticles surface was evaluated using FT-IR. The OXDH-PdNps have been used in carbon–carbon coupling reactions, namely, the Suzuki–Miyaura and Mizoroki–Heck reactions. Both of the reactions are carried out under phosphine-free conditions to provide better yields. The nanocatalyst can be easily recovered and reused for six consecutive catalytic cycles without any significant loss in its catalytic activity. 相似文献
9.
Four novel monodentate phosphorus-coordinated palladium(Ⅱ) complexes derived from 3,5-disubstituted-1H-1,2,4-diazaphospholes were developed as efficient catalyst for Mizoroki-Heck reactions of aryl halides with electron-deficient olefins. The role of these monophosphine ligands in catalysis was illustrated by control experiments using Pd salt and ligands as combined catalyst. 相似文献
10.
Ankita Chakraborty Sudipto Debnath Tanmoy Ghosh Dilip K. Maiti Swapan Majumdar 《Tetrahedron》2018,74(40):5932-5941
A sustainable route for the N-1 alkylation of imidazole and benzimidazole derivatives has been developed under volatile organic solvent free condition in alkaline water-SDS system. Incorporation of SDS in the reaction medium enhances the reaction rate by suppressing the solubility issue that arises for different substrates. This method provides high yield of the alkylated product in a shorter reaction time. For reactive alkyl halides reaction proceeds at ambient temperature whereas in the cases of less reactive alkyl halides require 55–60?°C to complete alkylation process. N-alkylation induced ring opening of the heterocyclic ring in benzimidazole derivatives to multifunctional aromatic compounds were noticed at 60?°C when more than two equivalents of alkyl halide was used. 相似文献
11.
The first examples of a Type 3 ring opening reaction of cyclopropanated oxabenzonorbornadiene (CPOBD) were found to occur using alcohol nucleophiles under acid catalyzed conditions, yielding seven-membered rings via ring expansion. Optimization of the reaction determined the ideal conditions to be 10?mol% pTsOH at 40?°C using excess alcohol nucleophile as the solvent. The scope of the reaction investigated diverse alcohol nucleophiles and bridgehead substituents on the CPOBD; in both cases the steric properties of the substituent was found in influence the yield of the reaction. Alternative Type 3 products were observed when the bridgehead substituent was an ethyl or hydroxymethyl group and limited examples of Type 3 products were formed using a palladium catalyst with alcohol nucleophiles. Mechanisms have been proposed for the formation of the Type 3 product as well as the alternative Type 3 products. 相似文献
12.
We have investigated the reactivity of the unsymmetrical H-spirophosphorane (HSP) ligand HP(OCMe2CMe2O)(OCH2CMe2NH) 1 towards different palladium(II) precursors and synthesised the mononuclear complexes [PdCl2{P(OCMe2CMe2O)OCH2CMe2NH2}] 2 and [PdCl(C3H5){P(OCMe2CMe2O)OCH2CMe2NH2}] 3. The structural features of the compounds are characterised by spectroscopic methods as well as single crystal X-ray diffraction studies. The complexes are shown to be remarkably active precatalysts for the Heck and Hiyama cross-coupling reactions. The products of the C-C bond formation reactions were obtained with high conversion and stereoselectivity. Mechanistic studies of the Heck reaction reveal that, besides homogenous precatalysts, also heterogeneous Pd(0) nanoparticles are involved in the catalytic process. 相似文献
13.
《Arabian Journal of Chemistry》2019,12(8):2098-2103
Task specific ionic liquid as a novel and environmental eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. This ionic liquids as solvent, catalyst and reagent afforded the corresponding thiocyanohydrins and azidohydrines with good regioselectivity and very short reaction times. The desired thiocyanohydrins and azidohydrines in 83–93% isolated yields. 相似文献
14.
Zhong-Quan Liu 《Tetrahedron letters》2005,46(6):1023-1025
Reaction of N-tosyl aziridines with nitric oxide affords the corresponding ring-opened products in regio-, stereoselectivities and excellent yields. 相似文献
15.
通过简单的一锅两步法制备了三氟金属(铝,钛,锆)接枝介孔SBA-15 (AlTf/S,TiTf/S,ZrTf/S)固体酸材料,并通过XRD,N2吸附,TGA,FTIR,原位吡啶FTIR和元素分析对这些材料进行了详细的表征.其中,ZrTf/S能够高效催化环氧化物温和条件下被胺或醇开环生成对应β-氨基醇或β-烷氧基醇,并且催化剂能循环利用.ZrTf/S相较于AlTf/S和TiTf/S酸性最强,因而催化活性也最高. 相似文献
16.
A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multisite phase-transfer catalyst,α,α′,α″-N-hexakis(triethylammoniummethylene chloride)-melamine,is developed.A variety ofβ-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 相似文献
17.
Luc Martinon Stéphane Azoulay E. Peter Kündig 《Journal of organometallic chemistry》2004,689(23):3831-3836
A Pd-catalyzed three-component assembling of highly functionalized 4-benzyl-(and allyl-)pyrrolidines was achieved based on a combination of allyl amines, gem-diactivated alkenes, and unsaturated halides (or triflate). 相似文献
18.
A convenient catalyst system consisting of Pd(OAc)2, PPh3, K3PO4 and DMSO was found to be effective for the coupling reaction of aryl halides with terminal alkynes as well as the deacetonative coupling reaction using a 4-aryl-2-methylbut-3-yn-2-ol as a terminal alkyne precursor. An iminophosphine as a ligand worked more effectively for some combination of substrates than triphenylphosphine. 相似文献
19.
A highly effective and mild protocol for ring opening of epoxides with NH 4 SCN in the presence of catalytic amount of a multisite phase-transfer catalyst, α,α',α" -N-hexakis(triethylammoniummethylene chloride)-melamine, is developed. A variety of b-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 相似文献
20.
Rapid and efficient ring opening of epoxides catalyzed by a new electron deficient tin(IV) porphyrin
The new electron deficient tin(IV) tetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(tpp)(OTf)2], was used as an efficient catalyst for the alcoholysis, hydrolysis and acetolysis of epoxides. Conversion of epoxides to thiiranes and acetonides were also performed efficiently in the presence of this catalyst. 相似文献