dN离子在三角场中的基矢及有关矩阵元

通过选用合适的单电子基矢, 使按群链[(O?D_3?C_3)×SU(2)]~N构成的多电子基矢, 成为dN体系D_3?C_3旋量群不可约表示的基矢或其两个一维不可约表示直和的基矢。讨论了有关矩阵元和顺磁参数的计算。     

f3组态离子在四角场中的基矢矩阵元

通过选用与群链[(O⊃D₄⊃C₄)×SU(2)]相匹配的单电子基矢,使其直积构成多电子fN体系的O⊃D₄⊃C₄旋量群的不可约表示的基矢,并讨论了有关的Coulomb矩阵元、Casimir矩阵元、旋-轨偶合矩阵元和晶体场作用矩阵元.     

Tb~(3+):LaBr_3能级分析

本文对Ln~(3+):LaCl_3和Ln~(3+):LaBr_3体系进行晶场能级分析,其主要目的有二:(一)对已测得的实验能级进行理论计算和归宿;(二)探讨能级间的相互作用及等价算符方法和不可约张量方法对该体系的适合程度。理论计算采用投影算符方法构成J=6,5,4,3,2,1,0的D_(3h)不可约表示基矢。在整个计算过程中,晶场矩阵由相同不可约表示的基矢构成。对~7F(J=6,5,4,3,2,1,0)本文分别应用等价算符方法(略去晶场J相互作用即略去所谓的晶场J混合作用)和不可约张量方法(考虑晶     

(S,S)-TsDPEN-Ru催化不对称氢转移还原β-胺基酮及在度洛西汀合成中的应用

报道了甲酸/三乙胺体系中,(S,S) -TsDPEN-Ru络合物催化的不对称氧转移反应合成(S)-γ-胺基醇的方法.考察了不同底物的反应性能,β-单/二烷基胺基-2-噻吩酮在该还原体系中氧解得到1-(2-噻吩基)-1-丙酮;氮原子上吸电子基取代的底物以高收率、高立体选择性(＞95％e.e.)得到还原产物.将这一反应用于...     

等性扩展基杂化轨道的构造

杂化轨道理论近来有了长足的发展,杂化轨道的构造方法主要有群论方法最大重叠方法,自然杂化轨道法和其它以分子轨道为基础构造杂化轨道的方法等。其中最大重叠杂化轨道不仅满足正交化条件而且能较定量地考虑到配体轨道的作用,因而已经得到广泛应用。本文在最大重叠原理的基础上得到了扩展基杂化轨道的解析形式。扩展基杂化轨道对一给定几何构型的分子M(X_1X_2…X_n),其中心原子M的n个杂化轨道与诸配体{X_i}形成一组方向键。M的杂化轨道(HO)和原子轨道(AO)可分别作为该分子对称操作群的表示之基。这两种不同基的表示进行约化之后,属于同一不可约表示的HO和AO是线性相     

手性Binap-Ru(Ⅱ)催化剂用于不对称加氢反应的研究进展

手性联二萘基双膦配体Binap由一对2-二苯基膦萘基连接1和1'位组成,具C2-对称框架轴向手性,比旋光度达到±234°.Binap配体可以和许多过渡金属形成稳定的螯合状配合物,在催化过程中通过金属中心"传递"立体空间效应,诱导不对称催化反应.针对Binap-Ru(Ⅱ)催化体系,以体系中形成的稳定配合物为主线,详细介绍反应过程中涉及到的底物分子种类、反应条件、产物的对映选择性等以及可能的反应机理,以期对该体系有深入的理解.特别关注该体系的不对称催化应用合成.     

(S)-联萘酚钛体系催化3-噻吩铝试剂对酮的不对称加成反应（英文）

含噻吩基团的的手性芳香醇是自然界重要的活性物质,其基本结构单元广泛地存在于生物活性物质和医药中.报道了(S)-联萘酚和Ti(OiPr)_4催化3-噻吩基铝试剂对酮的不对称加成反应,以较高的产率和优异的立体选择性(高达91%ee)得到相应的含有3-噻吩基乙醇.该催化体系具有广泛的适应性,能够适合含有吸电子和供电子基团的各种酮的不对称加成,得到相应的3-噻吩基乙醇.     

(2S,5S)-1-氮-3-氧-2,4,4-三苯基二环[3.3.0]辛烷衍生物的合成及表征

从不对称催化反应问世以来,人们一直在寻找高效、廉价、易制备的手性催化剂。Himto Nakano等人用(S)-二苯基脯胺醇和2-二苯膦基苯甲醛合成了手性化合物(2S,5S)-1-氮-3-氧-2-二苯膦基苯-4,4-二苯基二环[3．3．0]辛烷,并与钯络合来催化不对称反应。     

N-(4,6-二甲氧基嘧啶-2-基)-N'-磷酰基脲类衍生物的合成及生物活性

利用二氯代磷酰基异氰酸酯与4,6-二甲氧基-2-氨基嘧啶的加成反应合成了中间体N-(4,6-二甲氧基嘧啶-2-基)-N'-二氯代磷酰基脲(Ⅰ).Ⅰ与2倍的醇或胺反应得到对称双取代磷酰基脲类化合物Ⅱa_Ⅱi;Ⅰ与1倍的胺反应得到氯代磷酰基脲类化合物Ⅲa_Ⅲe,再与1倍的醇反应则得到不对称双取代磷酰基脲类化合物Ⅳa_Ⅳg.生物活性测定结果表明,化合物Ⅱ、Ⅲ和Ⅳ均显示一定除草活性.     

取代基自旋离域参数O_T——4.若干因素对三氟苯乙烯热环化二聚反应动力学测定精确度的影响

三氟苯乙烯(TFS)的热环化二聚反应是经过1,4-双自由基机理进行的。这一反应的溶剂效应和取代基效应已对此提供了有力的证据。此反应体系又具有一些与众不同的特色,如:(1)取代 TFS 的~(19)F NMR 参数可以直接反映双键π电子云的极化程度;(2)热环化二聚反应的过渡态具有偶极上的对称     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.