纳米金属粉对高氯酸铵热分解特性的影响

催化性能;纳米金属粉对高氯酸铵热分解特性的影响     

烯烃羰化—步制醇铑系催化新体系的研究

羰基铑催化剂由于其加氢性能较弱，在羰基化反应的研究中，通常仅作为烯烃氢甲酰化制醛的催化剂。产物中得不到醇。本文则报道了以Ｒｈ＿２（ＡｃＯ）＿４和Ｒｈ＿６（ＣＯ）＿１６为催化剂，在一个反应器内进行烯烃氢甲酰化，加氢制醇的研究。系统考察了Ｒｈ／Ｐｂｕ＿３／ＥｔＯＨ催化体系受各种反应条件的影响。在最佳反应条件下，烯烃转化率达１００％。对醇选择性亦在９９．５％以上，正异构比在２以上．为烯烃一步制醇建立了铑系催化新体系。文中并利用红外光谱测定了反应过程的催化剂物种．实验证明，由烯烃一步制醇是由烯烃首先进行氢甲酰化反应，然后由生成的醛进一步加氢成醇的一个串联反应过程。前一步骤反应速度较快，２ｈ内可使９５％以上的烯烃转化为醛，后面由醛加氢成醇则进行缓慢，在１００—１２０℃下，至少２２ｈ，才能使醛全部转化为醇。     

三核钨钼簇合物对苯乙烯氧化反应的催化

关于烯烃的催化氧化,报道较多。Takao等研究了苯乙烯在Ir和Rh络合物存在下的氧化反应;Collman曾报道环己烯在Vaska络合物[IrX(CO)(PPh_3)_2]催化下氧化成环己酮和环已烯氧化物。本文采用Cotton合成的簇合物[W_3O_2(CH_3CO_2)_6(H_2O)_3]Br_2·     

Aerobic asymmetric oxygenation catalysis: a well forgotten… future?

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TMEDA-CATALYZED SYNTHESIS OF N-ARYL-N′-ETHOXYCARBONYL THIOUREA AND ARENE (OR POLYMETHYLENE)-BIS-ETHOXYCARBONYLTHIOUREA DERIVATIVES

A novel and efficient method for synthesis ethoxycarbonyl isothiocyanate and ethoxycarbonyl thioureas catalyzed by TMEDA is reported. A series of N-aryl-N′-ethoxycarbonyl thioureas and arene (or polymethylene)-bis-ethoxycarbonyl thiourea derivatives have been synthesized in good-to-excellent yields via this method at room temperature.     

A Facile Oxidation of Thiols to Disulfides Catalyzed by CoSalen

Abstract

A convenient and facile catalytic oxidation of thiols to the corresponding disulfides is described using CoSalen as the catalyst and air as the oxidizing agent. This new approach provides an efficient method for the preparation of symmetrical disulfides in high yields and under mild conditions.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Spectroscopic Identification of Products 3a–3l.]     

Asymmetric Synthesis of Novel Axially Chiral 2,2'-Bipyridine N,N'-Dioxides Bearing α-Amino Acid Residues and Their Applications in Enantioselective Allylation of Aromatic Aldehydes with Allyltrichlorosilane

A series of novel axially chiral 2,2′‐bipyridine N,N′‐dioxides bearing C₁ or C₂‐symmetry have been synthesized by the use of enantiopure α‐amino acids as chiral sources. The absolute stereochemistry of the axial chirality of these organocatalysts has been clearly assigned by means of CD measurements together with literature protocols. The reactivities and enantioselectivities of these organocatalysts have been examined in the reactions of aromatic aldehydes with allyltrichlorosilane, thus providing the desired products with moderate yields and enantioselectivies.     

A Novel and Efficient Synthesis of 2,3-Dichloroquinoline

2,3-Dichloroquinoline was prepared in three steps in good overall yield from commercial 3-bromoquinoline via N-oxide formation and rearrangement to 3-bromocarbostyril, followed by a one-pot conversion to 3-bromo-2-chloroquinoline and halogen exchange to the title compound.     

Highly selective synthesis of novel (E)-styrylsilatranes via ruthenium-catalyzed trans-silylation

Protocols for the synthesis of cage-substituted 1-vinylsilatranes have been developed and updated. The 1-vinylsilatranes with organic substituents attached to silatrane cage were functionalized in ruthenium-catalyzed trans-silylation with olefins, leading to novel styrylsilatranes in high yields.