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排序方式: 共有925条查询结果,搜索用时 15 毫秒
1.
A variety of aryl nitriles were prepared in excellent yields from the palladium acetate catalyzed coupling of aryl halides with Zn(CN)2 using polymer-supported triphenyl phosphine as the ligand and dimethylformamide as solvent under microwave irradiation conditions. 相似文献
2.
Xiangdong Liu Hongwei Liu Kexu Yuan Huiping Du 《International Journal of Infrared and Millimeter Waves》1991,12(9):1023-1034
According to the angular-spectrum method, a radiation beam of an antenna horn in the Fresnal region is decomposed into the plane waves with the fast Fourier transform algorithm and the waves diffracted from a reflection grating are superposed as a diffracted beam. Compared with the reflected beam from the same size mirror, the radiation half width of the diffracted beam from a grating is narrower and its lateral shape is shift. These performances have been experimentally verified at Ka-band by: (1). The relative diffraction efficiencies in the first order with two triangular gratings which is put along propagating direction of a beam produced by a conical lens-horn. (2). H-plane lateral width with power—3dB lapsed of the focus beam from a grating and a mirror in a grating spectrometer for millimeter waves (25–100 GHz). 相似文献
3.
Adriana Tudose 《Tetrahedron letters》2006,47(48):8529-8533
Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product. 相似文献
4.
Ioannis N. Lykakis 《Tetrahedron letters》2004,45(41):7645-7649
Decatungstate photocatalyzes the oxidation of aryl alkanes to the corresponding tertiary hydroperoxides and alcohols, in the presence of molecular oxygen. The addition of triethylsilane to the reaction mixture substantially increases the proportion of hydroperoxide formed. 相似文献
5.
J.S. Yadav B.V. Subba Reddy V. Sunitha K. Srinivasa Reddy K.V.S. Ramakrishna 《Tetrahedron letters》2004,45(42):7947-7950
Aryl amines react with endocyclic ene-carbamates such as tert-butyl 2,3-dihydro-1H-1-pyrrolecarboxylate and tert-butyl 1,2,3,4-tetrahydro-1-pyridinecarboxylate, on the surface of montmorillonite KSF clay under mild conditions to afford the corresponding 3-aminopropylhexahydropyrrolo[3,2-c]quinoline or 4-aminobutyloctahydrobenzo[h][1,6]naphthyridine derivatives in excellent yields with moderate diastereoselectivity. 相似文献
6.
引言在定量和定性研究有机化合物的结构与性质的关系中,最广泛使用的是Hammett等所提出的σ_m、σ_p等取代基常数以及基团的诱导(场)效应和共轭效应常数。在建立基团的共轭效应常数方面,人们做了大量的工作,但多数工作是基于对基团的Hammett常数σ的人为分解上,建立的模型和分解方式(系数因子)不同,则得到不同的结果。另一方面纯理论计算工作大多引入较多参数,使计算复杂和使用不便。作者曾在建立表征诱导效应大小的 相似文献
7.
Hong She Wang Jun E. Zeng 《中国化学快报》2007,18(12):1447-1450
Synthesis of symmetrical diaryl sulfoxides from arenes and thionyl chloride in the presence of a catalytic amount of iodine at room temperature under solvent-free conditions is described.Mild reaction conditions,easy workup,high yield,and easily available catalyst are important features of this method. 相似文献
8.
报道了3-芳基四氢合萘-1-酮的烯醇硅醚在氧化碘苯-三氟化硼的协同作用下3-位芳基迁移到2-位,生成2-芳基-3-氟四氢合萘-1-酮的反应。当芳基是Ph-p-Cl-Ph、p-Me-Ph和p-MeO-Ph时,收率分别为80%、61%、10%和5%,并讨论了这一反应的机理。 相似文献
9.
G. R. Sudhakaran J. C. Sarker R. L. Bhattacharjee L. H. Johnston 《International Journal of Infrared and Millimeter Waves》1987,8(12):1531-1540
Submillimeter laser-Stark spectra have been observed for the isotopic species of methyl fluoride,13CH3F, using the 337 m line of the HCN laser. We have identified the multiplet transitions as JK=18K17K in the ground vibrational state. Ten distinct families with K=8, 9, 10, 11, 12, 13, 14, 15, 16 and 17 have been observed. Zero-field frequencies for all the transitions are given and in most cases with better accuracy than predicted from the previous constants. 相似文献
10.
A simple new protocol for the high yielding Suzuki-Miyaura cross-couplings of aryl chlorides with aryl boronic acids using a palladium/imidazolium salt catalytic system is presented. The first examples of a palladium/imidazolium salt protocol for sp3-sp3 Suzuki-Miyaura couplings of alkyl halides are also disclosed. 相似文献