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1.
Qiaoling Wang 《Tetrahedron letters》2008,49(18):2916-2921
Catalytic carbonylative Negishi cross-coupling reactions are described. This method readily provides various enones from enol triflates and diorganozinc reagents with catalytic amounts of nickel(II) chloride-4,4′-dimethoxyl-2,2′-bipyridyl under carbon monoxide atmosphere. The rate of carbon monoxide insertion is increased by the addition of lithium or magnesium halides and the use of polar solvents. Alkenyl iodides can also be used in place of enol triflates. 相似文献
2.
Diazonium salts, precisely arenediazonium o-benzenedisulfonimides, have been used for the first time as efficient electrophilic partners in Negishi coupling reactions. The synthetic protocol was general, easy and gave biaryls in satisfactory yields (34 examples, average yield 69%). o-Benzenedisulfonimide was recovered at the end of the reactions and reused to prepare the starting salts once again. 相似文献
3.
Ricardo F. Schumacher 《Tetrahedron letters》2008,49(3):538-542
3-Iodoselenophene derivatives undergo a direct Negishi cross-coupling reaction with several organozinc compounds in the presence of a catalytic amount of Pd(PPh3)4 in THF at room temperature. This cross-coupling reaction proceeded cleanly under mild conditions and permitted the formation of polyaromatic compounds in good yields. 相似文献
4.
Reactions of alkyl halides with arylmagnesium bromides in the presence of cobalt(II)(diphosphine) complexes are discussed. Treatment of 1-bromooctane with phenylmagnesium bromide with the aid of a catalytic amount of CoCl2(dppp) [DPPP=1,3-bis(diphenylphosphino)propane] yielded octylbenzene in good yield. The reaction mechanism would include single electron transfer from an electron-rich cobalt complex to alkyl halide to generate the corresponding alkyl radical. The mechanism was justified by CoCl2(dppe)-catalyzed [DPPE=1,2-bis(diphenylphosphino)ethane] sequential radical cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives that yielded benzyl-substituted cyclopentane skeletons. 相似文献
5.
Naoki Kakusawa 《Journal of organometallic chemistry》2005,690(12):2956-2966
The reaction of ethynylstibanes (1a-g) with vinyl halides or triflate in the presence of a palladium catalyst led to the formation of cross-coupling products (5a-g, 10-12) in good to moderate yield, along with homo-coupling products (6a-g). A similar reaction of ethynyldiphenylstibane (1a) with aryl iodides (13a-i) also gave cross-coupling products (14a-i), although the yields were relatively low. The yields of the cross-coupling products were highly dependent on the nature of the solvent employed, and good results were obtained when the reaction was carried out in HMPA or amines such as diethylamine and morpholine. The results imply that HMPA and amine used as solvents facilitate transmetallation of the ethynyl group on 1 to the palladium by intermolecular coordination between antimony and oxygen (for HMPA) or nitrogen (for amine). 相似文献
6.
A mild, functional group tolerant palladium-catalyzed Negishi coupling of pyrazole triflates and nonaflates with alkyl, benzyl, and aryl zinc halides has been developed. It allows quick access to 3-substituted pyrazole analogs at late stage via common synthetic intermediates. 相似文献
7.
Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II) complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products. In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and allylzinc bromide, respectively, in which the branched coupling product is the major product. 相似文献
8.
Total synthesis of the COPD biomarker desmosine via Sonogashira and Negishi cross-coupling reactions
Hiroto YanumaToyonobu Usuki 《Tetrahedron letters》2012,53(44):5920-5922
Desmosine, a crosslinking pyridinium amino acid of elastin, is an attractive biomarker for the diagnosis of chronic obstructive pulmonary disease (COPD). In this study, the total synthesis of (+)-desmosine is reported utilizing chemo- and regioselective Sonogashira and Negishi cross-coupling reactions in 15% yield over six steps. 相似文献
9.
The oxidative coupling of 2-naphthol and 3-hydroxy-2-naphthamide with various copper catalysts under an O2 atmosphere was performed. The reaction proceeded in a cross-coupling specific manner when the substrate has a secondary amido group. 相似文献
10.
A general Ni-catalyzed process for the cross-coupling of secondary alkylzinc halides and aryl/heteroaryl iodides has been developed. This is the first process to overcome the isomerization and β-hydride elimination problems that are associated with the use of secondary nucleophiles, and that have limited the analogous Pd-catalyzed systems. The impact of salt additives was also investigated. It was found that the presence of LiBF(4) dramatically improves both isomeric retention and yield for challenging substrates. 相似文献
11.
Rob van Asselt Kees Vrieze Cornelis J. Elsevier 《Journal of organometallic chemistry》1994,480(1-2):27-40
Zerovalent complexes of the type Pd(Ar-BIAN)(alkene), i.e. complexes containing the rigid bidentate nitrogen ligands bis(arylimino) acenaphthene (Ar = p-Tol, p-MeOC6H4, o-Tol,o,o′-Me2C6H3, o,o′-iPr2C6H3) and an electron-poor alkene have been shown to react with a variety of (organic) halides RX, including methyl, benzyl, aryl, acyl and allylic halides, to give the corresponding square planar divalent Pd(R)X(Ar-BIAN) or [Pd(η3-allyl)(Ar-BIAN)]X complexes. The new complexes obtained have been fully characterized and their fluxional behaviour in solution studied by 1H NMR spectroscopy. The rate of oxidative addition of iodomethane to Pd(p-Tol-BIAN)(alkene) complexes was found to decrease with increasing Pd-alkene bond strength, i.e. dimethyl fumarate fumaronitrile, but oxidative addition to the fumaronitrile complex was accelerated by irradiation with a mercury lamp. Oxidative addition of allylic ha 相似文献
12.
A series of nickel-salicylideneimines complexes were prepared in wild way and these complexes were stable to air and moisture. The nickel-salicylideneimines complexes exhibited good activity in catalyzing Grignard reagents with aryl halids to biphenyl derivatives and the more fluorine atoms contained by N-substituted benzene moiety could function the better activity. 相似文献
13.
Vivek PolshettiwarManisha Nivsarkar Jyotiranjan AcharyaM.P Kaushik 《Tetrahedron letters》2003,44(5):887-889
Benzyltriethylammonium tetracosathioheptamolybdate [(C6H5CH2N(Et)3)6Mo7S24] has been found to be a superior sulfur transfer reagent for the conversion of alkyl halides to the corresponding disulfides in excellent yields under very mild reaction conditions. 相似文献
14.
The Pd-catalyzed reaction of [CpCo(S2C2(Ph)(Bpin))] (1, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaboronate) with 1-iodonaphthalene or 2-bromothiophene gave the cross-coupling product [CpCo(S2C2(Ph)(Ar))] (Ar = 1-Np (4) or 2-Th (5)), although an early paper described the reaction of 1 with 3-bromopyridine or 9-bromoanthracene (Ar = 3-Py (2) or 9-Anth (3)). The boronation of the brominated precursor [CpCo(S2C2(p-C6H4Br)(H))] (7) with Bpin-H in the presence of Pd catalyst gave the expected boronated product [CpCo(S2C2(p-C6H4Bpin)(H))] (8) but also underwent an unexpected direct boronation on the dithiolene carbon to form [CpCo(S2C2(p-C6H4Br)(Bpin))] (9). The brominated complex 7 or [CpCo(S2C2(Ph)(p-C6H4Br))] (10) was synthesized by thermal reaction and the microwave-enhanced reaction relatively gave better yield with shorter reaction time than that of the conventional heating reaction. The cross-coupling reactions of the boronated or [CpCo(S2C2(Ph)(p-C6H4Bpin))] (11) with aryl halides successfully produced the corresponding cross-coupling products such as [CpCo(S2C2(p-C6H4Py)(H))] (12) or [CpCo(S2C2(p-C6H4Anth)(H))] (13) from 8 and [CpCo(S2C2(Ph)(p-C6H4Py))] (14) from 11. The structures of 7, 9, 11, 12, 13 and 14 were determined by X-ray diffraction studies. Electronic absorption maxima (λmax) due to dithiolene LMCT in dichloromethane solution can be modified in the range of 574-602 nm by a substituent effect on the dithiolene ring. Redox potentials obtained from CV measurement were also reported. 相似文献
15.
A facile synthetic procedure for chiral tryptophan derivatives using Negishi cross-coupling reaction of serine-derived iodoalanine with 3-haloindole is described. The best result was obtained when the reaction of N-tosyl-3-bromoindole with N-Cbz-iodoalanine methyl ester was carried out by the combination of Pd2(dba)3 and sterically hindered ferrocenyl ligand Q-PHOS. This reaction condition not only gave the desired tryptophan derivative as high as 76% yield, but also suppressed the formation of undesired products, the dehalogenated indole and the homodimer of indole, which were difficult to separate. This reaction was extended to the synthesis of various tryptophan derivatives having substituents on the benzene ring. The characteristic of this reaction is the practical biomimetic synthesis of chiral tryptophan derivatives in one-step. 相似文献
16.
The Negishi cross-coupling reaction of vinylic- and aryltellurides with heteroarylzinc chlorides catalyzed by PdCl2/CuI is described. This cross-coupling reaction is general and permits the formation of a new sp2-sp2 carbon bond in good yields and high stereoselectivity. 相似文献
17.
Hunter HN Hadei N Blagojevic V Patschinski P Achonduh GT Avola S Bohme DK Organ MG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7845-7851
Negishi cross-coupling reactions were analyzed in solution by mass spectrometry and NMR spectroscopy to identify both the effect of LiBr as an additive as well as the purpose of 3-dimethyl-2-imidazolidinone (DMI) as a co-solvent. The results suggest that the main role of DMI is to facilitate a higher order bromozincate formation during the addition of LiBr. 相似文献
18.
Michael Werner 《Journal of organometallic chemistry》2009,694(2):190-5635
Diacetylplatinum(II) complexes [Pt(COMe)2()] ( = bpy, 3a; 4,4′-t-Bu2-bpy, 3b), obtained by the reaction of [Pt(COMe)2X(H)()] with NaOH in CH2Cl2/H2O, were found to undergo oxidative addition reactions with halogens (Br2, I2) yielding the platinum(IV) complexes (trans, OC-6-13)/(cis, OC-6-32) [Pt(COMe)2X2()] ( = bpy, X = Br, 4a/4b; I, 4c/4d; = 4,4′-t-Bu2-bpy, X = Br, 4e/4f; I, 4g/4h). The diastereoselectivity of the reactions proved to be strongly dependent on the solvent. The oxidative addition of (SCN)2 resulted in the formation of (OC-6-13)-[Pt(COMe)2(SCN)2()] ( = bpy, 4i; 4,4′-t-Bu2-bpy, 4j). In a reaction the reverse of their formation, the diacetylplatinum(II) complexes 3 underwent oxidative addition with anhydrous HX (X = Cl, Br, I), prepared in situ from Me3SiX/H2O, yielding diacetyl(hydrido)platinum(IV) complexes [Pt(COMe)2X(H)()] ( = bpy, X = Cl, 5a; Br, 5b; I, 5c; = 4,4′-t-Bu2-bpy, X = Cl, 5d; Br, 5e; I, 5f). Furthermore, diacetyldihaloplatinum complexes 4 were found to undergo reductive elimination reactions in boiling methanol yielding acetylplatinum(II) complexes [Pt(COMe)X()] ( = bpy, X = Br, 6b; I, 6c; = 4,4′-t-Bu2-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and 1H and 13C NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis. 相似文献
19.
Li-Xiong Shao 《Tetrahedron》2007,63(48):11938-11942
We report herein copper(I)-catalyzed cross-coupling reactions of alkenyl halides with alkynes for the synthesis of 2-alkynyl-buta-1,3-dienes in good to excellent yields. This procedure is the first example for the synthesis of enynes catalyzed by catalytic amount of copper(I) alone in the absence of palladium and any ligand at relatively lower temperature. 相似文献
20.
Ulrich Siemeling Frauke Bretthauer Clemens Bruhn 《Journal of organometallic chemistry》2010,695(4):626-408
[Pt(PPh3)4] reacts smoothly and swiftly at room temperature with asparagusic acid and with selected amide and ester derivatives of this cyclic disulfide to afford PtII dithiolate chelates of the type cis-[Pt{CRR′(CH2S)2}(PPh3)2]. The crystal structures of three such products are reported. 相似文献