Efficient Palladium‐Catalyzed Aminocarbonylation of Aryl Iodides Using Palladium Nanoparticles Dispersed on Siliceous Mesocellular Foam

A highly dispersed nanopalladium catalyst supported on mesocellular foam (MCF), was successfully used in the heterogeneous catalysis of aminocarbonylation reactions. During the preliminary evaluation of this catalyst it was discovered that the supported palladium nanoparticles exhibited a “release and catch” effect, meaning that a minor amount of the heterogeneous palladium became soluble and catalyzed the reaction, after which it re‐deposited onto the support.     

Palladium‐Catalyzed Aminocarbonylation of Allylic Alcohols

A benign and efficient palladium‐catalyzed aminocarbonylation reaction of allylic alcohols is presented. The generality of this novel process is demonstrated by the synthesis of β,γ‐unsaturated amides including aliphatic, cinnamyl, and terpene derivatives. The choice of ligand is crucial for optimal carbonylation processes: Whereas in most cases the combination of PdCl₂ with Xantphos ( L6 ) gave best results, sterically hindered substrates performed better in the presence of simple triphenylphosphine ( L10 ), and primary anilines gave the best results using cataCXium® PCy ( L8 ). The reactivity of the respective catalyst system is significantly enhanced by addition of small amounts of water. Mechanistic studies and control experiments revealed a tandem allylic alcohol amination/C?N bond carbonylation reaction sequence.     

Synthesis of Amides and Phthalimides via a Palladium Catalyzed Aminocarbonylation of Aryl Halides with Formic Acid and Carbodiimides

A novel method for the preparation of amides and phthalimides has been developed. The process involves a palladium catalyzed aminocarbonylation of an aryl halide, using a carbodiimide and formic acid as the carbonyl source. Experimental data suggest that the mechanistic pathway for this process involves in‐situ generation of carbon monoxide from the reaction of formic acid with a carbodiimide in the presence of a palladium catalyst. The method can be used to produce a variety of amides and N‐substituted phthalimides efficiently.     

Mycobacterium E3休止细胞催化烯烃立体选择性环氧化

初步研究了ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３的生长和产酶特性，利用ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３休止细胞催化烷羟化和烯烃环氧化，研究结果表明，烷烃不能被羟化，烯烃环氧化具有底物选择性，对烯丙基型底物ＸＣＨ２ＣＨ＝ＣＨ２（Ｘ＝Ｈ，Ｃｌ，Ｂｒ，ＯＨ）取代基大小显著性环氧化活性，ＭｙｃｏｂａｃｔｅｒｉｕｍＥ３中烯烃单加氧酶和另一种结构未知的酶的存在导致烯烃环氧化过程中存在环氧化物的立体选择性形成和非立体选择     

Hydrophosphorylation of Terminal Alkynes Catalyzed by Palladium

A series of new 1-aryl-, 1-heteroaryl-, and 1-alkylethenylphosphonates was prepared by hydrophosphorylation of terminal acetylenes catalyzed by palladium. A stable in air complex Pd₂(dba)₃·CHCl₃ was applied as catalyst. The reaction mechanism is discussed.     

Arylation of Substituted Anilines Catalyzed by Palladium

Arylation catalyzed by palladium complexes of substituted anilines obtained by modification of 2,4,6-trinitrotoluene makes possible preparation of various diaryl- and arylheterylamines in high yields.     

Carbonylation of Difluoroalkyl Bromides Catalyzed by Palladium

Although important progress has been made in the fluoroalkylation reactions, the transition‐metal‐catalyzed carbonylative fluoroalkylation reaction remains challenging so far. Herein, we report the first example of a Pd‐catalyzed carbonylation of difluoroalkyl bromides with (hetero)arylboronic acids under one atmosphere pressure of CO. The reaction can also be extended to the aryl potassium trifluoroborate salts. The advantages of this protocol are synthetic simplicity, broad substrate scope, and excellent functional group compatibility. The resulting difluoroalkyl ketones can serve as versatile building blocks for the synthesis of various useful fluorinated compounds.     

Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino‐Isocyanates

The ubiquity of nitrogen heterocycles in biologically active molecules challenges synthetic chemists to develop a variety of tools for their construction. While developing metal‐free hydroamination reactions of hydrazine derivatives, it was discovered that carbazates and semicarbazides can also lead to alkene aminocarbonylation products if nitrogen‐substituted isocyanates (N‐isocyanates) are formed in situ as reactive intermediates. At first this reaction required high temperatures (150–200 °C), and issues included competing hydroamination and N‐isocyanate dimerization pathways. Herein, improved conditions for concerted intramolecular alkene aminocarbonylation with N‐isocyanates are reported. The use of βN‐benzyl carbazate precursors allows the effective minimization of N‐isocyanate dimerization. Diminished dimerization leads to higher yields of alkene aminocarbonylation products, to reactivity at lower temperatures, and to an improved scope for a reaction sequence involving alkene aminocarbonylation followed by 1,2‐migration of the benzyl group. Furthermore, fine‐tuning of the blocking (masking) group on the N‐isocyanate precursor, and reaction conditions relying on base catalysis for N‐isocyanate formation from simpler precursors resulted in room temperature reactivity, consequently minimizing the competing hydroamination pathway. Collectively, this work highlights that controlled reactivity of aminoisocyanates is possible, and provides a broadly applicable alkene aminocarbonylation approach to heterocycles possessing the β‐aminocarbonyl motif.     

Useful Sialic Acid Modifications Catalyzed by Palladium

A regio‐ and stereocontrolled solution for a selective modification at the C‐2 or C‐4 position of N‐acetylneuraminic acid involves the use of allylic substitution catalyzed by palladium. As illustrated in the scheme, regioselective malonylation is under the strict influence of the ligands associated with the allylpalladium complex.

     

Unconventional Allylation of Norbornadiene Catalyzed by Palladium Complexes

A new catalytic system based on palladium complex compounds for the unconventional allylation of norbornadiene with allylic esters of carboxylic acids is developed. The structure of reaction products is determined and the factors affecting their ratio are found. Comparative analysis of the palladium and nickel catalytic systems is performed.     

Vinylation of Alkyl Halides Catalyzed by Palladium Catalyst

The palladium catalyzed vinylation of alkyl halides, especially benzyl chlorides, with a variety of olefins has been studied. A possible free radical mechanism was proposed.     

Highly Stereoselective Cyclopropanation of Olefins Catalyzed by a Novel C 3-Symmetric Arsine

A novel C ₃-symmetric arsine was employed in the one-pot cyclopropanation of olefins with carbonyl-stabilized arsonium ylides formed in situ from phenacyl bromide in the presence of NaHCO₃. This new arsine demonstrates good stereoselectivity and activity in the one-pot cyclopropanation of arylidenemalononitrile.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

钯催化的脱羧基烷基化反应

钯催化的脱羧基烷基化反应是构建碳碳键特别是手性碳的有效手段,其催化活性高,反应条件温和,对映选择性好.近年来该领域取得了长足的进步.介绍了5年来钯催化的脱羧基烷基化反应,主要是钯催化的对映选择性Tsuji反应及其在天然产物合成中的应用.     

Selective Palladium‐Catalyzed Aminocarbonylation of Olefins to Branched Amides

A general and efficient protocol for iso‐selective aminocarbonylation of olefins with aliphatic amines has been developed for the first time. Key to the success for this process is the use of a specific 2‐phosphino‐substituted pyrrole ligand in the presence of PdX₂ (X=halide) as a pre‐catalyst. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino‐acid derivatives, to give the corresponding branched amides generally in good yields (up to 99 %) and regioselectivities (b/l up to 99:1).     

钯催化 1,3-丁二烯羧酯化合成 3-戊烯酸甲酯

 以 1,3-丁二烯、CO 和甲醇为原料, 进行羧酯化反应合成 3-戊烯酸甲酯是 Altam 路线生产己内酰胺绿色工艺的关键步骤. 将 Pd 与三齿 N-杂环配体或双膦配体组成的催化体系用于 1,3-丁二烯的羧酯化反应中, 其中乙酸钯/2,6-二 (3,5-二甲基吡唑基) 吡啶催化剂表现出中等的催化活性, 在 150 ºC, p(CO) = 6.0 MPa 的优化条件下反应 6 h, 1,3-丁二烯转化率为 78.8%, 3-戊烯酸甲酯选择性达 92.2% (TON = 226); 而乙酸钯/2,2?-二 (二苯基膦基) 苯醚催化体系的活性更高, 在优化反应条件下, 1,3-丁二烯转化率达 90.4%, 3-戊烯酸甲酯选择性为 91.6% (TON = 181). 在 200 ºC 及类似的羧酯化反应条件下, 1,3-丁二烯发生二聚反应, 其转化率为 99% 以上, 二聚产物 4-乙烯基-1-环己烯选择性高于 96%.