钯—膦—酸体系催化烯烃氢酯基化反应

众所周知,酯是重要的精细化工产品。有些酯可作水果香精,有些酯是高级酒香的重要成分,己二酸二辛酯和癸二酸二辛酯则是高级增塑剂。通常,酯是用羧酸和醇反应制得。若能利用来自石油化工厂的烯烃和CO代替得之不易的羧酸来生产酯类。将具有明显的实际意义。国外曾试探过许多过渡金属包括钴、铑、铱等的配位催化体系对烯烃进行氢酯基化的催化反应,其中以钯膦体系效果最佳。国内,已有二、三个研究小组对钯膦体系进行探索,但未见有关钯膦酸催化剂体系方面的报道。本文介绍我们在钯膦酸体系催化氢酯基化反应的一些实验结果。     

手性配体DDPPI-Pd(Ⅱ)催化α-烯烃不对称氢酯基化反应的研究

考察了手性双膦配体DDPPI在钯催化1-辛烯及官能化端烯的不对称氢酯基化反应中的手性诱导作用，最高得到了45．2％的ee值．其中在1-辛烯的不对称氢酯基化反应中，考察了不同的膦-钯比、反应温度、压力、不同的溶剂、不同的钯催化剂前体以及助催化剂对反应的影响．其中膦，钯比在2～4的范围内，催化反应获得了较高的光学产率；以丙酮作溶剂，得到较好的催化效果．     

钯-膦-酸体系催化烯烃氢酯基化反应研究进展

烯烃氢酯基化反应是羰基合成领域的重要分支之一,长期以来一直备受关注。目前已发展了钯基、铑基、钴基、钌基等众多催化体系,其中钯-膦-酸催化体系因具有反应条件温和、底物普适性良好、催化性能优异等优点而得到最广泛、最深入的研究。因此,我们对均相、非均相的钯-膦-酸催化体系在烯烃氢酯基化反应中的研究应用进行了简要综述,并对催化机理、催化剂组成和性能进行讨论,最后指出稳定性高、可回收性好的非均相钯-膦-酸催化体系将是该领域的研究重点。     

PdCl_2－CuCl_2－PPh_3催化剂立体选择催化烯烃氢酯基化反应

研究了以ＰｄＣｌ２－ＣｕＣｌ２－ＰＰｈ３为催化剂体系，甲基乙基酮、乙二醇二甲醚为溶剂，苯乙烯与一氧化碳及甲醇立体选择生成２－苯基丙酸甲酯的反应．对不同的催化剂前体催化烯烃氢酯基化反应进行了研究，得知ＣｕＣｌ２在此催化反应中起着立体控制作用．同时考察了影响反应的各种因素如溶剂、反应温度、反应压力、不同的膦配体等．实验结果表明，该反应的最佳条件是：反应温度８０℃，反应压力４．０—６．０ＭＰａ，反应时间２４ｈ，最好的溶剂是乙二醇二甲醚及甲基乙基酮．利用该催化剂体系对不同结构的烯烃催化反应进行了研究，发现该体系仅仅对苯乙烯类有较高的立体选择催化活性     

钯-手性膦催化降冰片烯的不对称氢酯基化反应

首次用Ｐｄ（ＯＡｃ）２－１，４∶３，６－双脱水－２，５－二（二苯基膦）－Ｌ－艾杜糖醇（ＤＤＰＰＩ）－ｐ－ＴｓＯＨ催化体系对降冰片烯进行了不对称氢酯基化反应，获得了较好的结果．考察了手性膦配体的结构以及磷原子与钯原子的摩尔比对反应的影响，发现在一个磷原子配位一个钯原子时，获得了较高的光学产率．同时考察了反应温度、反应压力及溶剂对降冰片烯不对称氢酯基化反应的影响，发现在１２０℃，５．０ＭＰａ，ｎ（Ｐ）／ｎ（Ｐｄ）＝１时，化学产率可达７１．６％，光学产率可达９２．２％．     

铑-膦配位催化烯烃氢甲酰化反应研究

本文研究了由Rh2(CO)4CI2分别与两种膦配体4－下丁苯基二苯基膦（1）和4－正辛苯基二苯基磷（2）形成的原位催化剂体系对烯烃氢甲酰化反应的催化性能。对影响反应的各种因素,如P／Rh物质的量比、反应温度、反应压力,不同烯烃等的影响作了探讨。结果表明,配体1、2与Rh2(CO4)CI2形成的原位催化剂体系的催化活性与选择性均高于结构相似的PPh3,在相同的条件下,不同烯烃的氢甲酰化反应活性依直链烯烃＞苯乙烯＞直链内烯＞环己烯的顺序递增。     

四膦配体的合成及其金属配合物催化烯烃氢甲酰化反应研究

合成了四膦配体Ｃ（ＣＨ２ＰＰｈ２）４，并研究了由钴－四膦配体组成的催化剂体系对烯烃氢甲酰化反应的催化作用．对反应的各种因素，如反应温度、反应压力、不同Ｐ／Ｃｏ比，不同烯烃等的影响作了探讨，并与不同膦配体体系催化烯烃氢甲酰化作对比，发现膦配体催化活性有如下顺序：Ｃ（ＣＨ２ＰＰｈ２）４≈Ｐｈ２Ｐ（ＣＨ２）２ＰＰｈ２＞Ｐｈ２Ｐ（ＣＨ２）３ＰＰｈ２＞Ｐｈ２ＰＣＨ２ＰＰｈ２＞Ｐｈ２Ｐ（ＣＨ２）４ＰＰｈ２．     

新的手性双膦配体的合成及其在苯乙烯不对称氢酯基化中的应用

以甘露醇和山梨醇为原料,合成了2个新的手性膦配体,并用这些新的手性膦配体与钯原位生成的催化剂体系催化苯乙烯的不对称氢酯基化反应,得到R构型的2－苯基丙酸甲酯,其ee值分别为28.5%和13.6%。     

PdCl2—CuCl2—PPh3催化剂立体选择催化烯烃氢酯基化反应

研究了以ＰｄＣｌ２－ＣｕＣｌ２－ＰＰｈ３为催化剂体系，甲基乙基酮、乙二醇二甲醚为溶剂，苯乙烯与一氧化碳及甲醇立体选择生成２－苯基丙酸酯的反应，对不同的催化剂前体催化烯烃氢酯基化反应进行了研究，得知ＣｕＣｌ２在此催化反应中起着立体控制作用，同时考察了影响反应的各种因素如溶剂、反应温度、反应压力、不同的膦配体等，实验结果表明，该反应的最佳条件是：反应温度８０℃，反应压力４．０－６．０ＭＰａ反应时间２４     

PdCl2—CuCl2—手性膦催化苯乙烯不对称氢酯基化反应

首次将ＰｄＣｌ２－ＣｕＣｌ２－手性磷催化体系用于苯乙烯不对称氢酯基化反应，获得了非常好的结果，在此不对称氢酯基化反应中，考察了手性配体的结构及磷原子与钯原子的摩尔比对反应的影响，在Ｐ／Ｐｄ＝２－４的范围内，获得了较高的光学产率；     

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%).     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

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.