Ni-catalyzed addition reaction of allylic selenides to alkynes

Nickel complex catalysts, Ni(cod)₂-2PPh₃ and Ni(cod)₂-dppb systems in particular, catalyze the addition reactions of phenyl allyl selenide to terminal alkynes to regioselectively afford 2-phenylseleno-1-allyl-1-alkenes in good to excellent yields. A mechanism that involves a η³-allyl-nickel complex is proposed on the basis of isolation, crystal structure determination and reactivity study of the complex.     

Rhodium-catalyzed addition of alcohols to terminal enones

[Rh(COD)(OMe)]₂ was found to catalyze the addition of aliphatic and aromatic alcohols with terminal enones to afford β-alkoxyketones in high yields.     

Catalytic enantioselective Michael addition of deconjugated butyrolactams to maleimides

The first catalytic enantioselective Michael addition of deconjugated butyrolactams to N-arylmaleimides is developed with the help of a bifunctional tertiary aminosquaramide catalyst. Unlike the widely explored and structurally related vinylogous nucleophile – deconjugated butenolides, deconjugated butyrolactams are found to be exclusively α-selective. The resulting highly substituted and densely functionalized products, bearing contiguous all-carbon quaternary and tertiary stereocenters, are formed in good yields with moderate diastereoselectivity and good to excellent enantioselectivity (up to 99:1 er).     

丙醛均相催化加氢制丙醇的研究

系统地研究了在４．０ＭＰａ氢压下，反应温度、催化剂浓度、溶剂等对丙醛均相加氢制正丙醇反应的影响，得出最佳反应条件为：氢压４．０ＭＰａ、温度８０℃，ＲｕＣｌ３·３Ｈ２Ｏ为催化剂前体，用量９８ｍｇ（０．３５ｍｍｏｌ），ＰＰｈ３为３９３ｍｇ（１．５ｍｍｏｌ），Ｒｕ／Ｐ摩尔比为１／４，ＤＭＦ为溶剂．在此条件下，丙醛转化率和正丙醇选择性可分别达９９％和９５％以上．求出了不同反应温度下的反应速度常数．以ＲｕＣｌ３－ＰＰｈ３为催化剂体系，丙醛加氢的活化能为７７．６２ｋＪ／ｍｏｌ     

Homogeneously catalysed isomerisation of allylic alcohols to carbonyl compounds

Isomerisation of allylic alcohols forms an elegant shortcut to carbonyl compounds in a completely atom-economical process that offers several useful applications in natural-product synthesis and in bulk chemical processes. This review focuses on the heart of isomerisation catalysis: the catalyst. Combinations of transition metals (from Group 4 to 10), ligands and reaction conditions are compared with respect to yield, turnovers, rate and selectivity. A selected number of clever solutions to synthetic problems are highlighted, such as the synthesis of enols and enolates, chiral carbonyl compounds and silyl substituted ketones. Furthermore, a general overview of the mechanisms proposed for the isomerisation of allylic alcohols is given while some catalyst systems are singled out to discuss mechanistic research.     

Chiral NHC ligands bearing a pyridine moiety in copper-catalyzed addition of diethylzinc to nitroalkenes

Chiral N-heterocyclic carbenes, derived from amino acids containing a pyridine ring, are effective ligands in the enantioselective copper-catalyzed addition of diethylzinc to β-nitroalkenes, which provides access to chiral nitroalkanes. The advantages of this process include high yields, broad and complementary substrate scope, and good to high enantioselectivities.     

Dependence of enantioselectivity on the ligand/metal ratio in the asymmetric Michael addition of indole to benzylidene malonates: electronic influence of substrates

Simple bis(oxazoline) ligands, especially azabis(oxazolines), can promote the copper(II)-catalyzed Michael addition of indoles to benzylidene malonates with up to >99 % ee (ee=enantiomeric excess), provided that the ligand/metal ratio is tuned meticulously with particular regard to the electronic properties of the substrate. Despite a common paradigm followed in many asymmetric catalyses, an excess of chiral ligand is not always beneficial. In fact any excess of ligand has to be avoided to reach excellent enantioselectivities when electron-rich benzylidene malonates are used. On the contrary, malonates carrying an electron-withdrawing group require an excess of ligand for an optimum ee value. A correlation of optical yields versus the sigma(I) values of several para substituents shows a sigmoid trajectory. In the presence of an additive, such as triflate, the significance of the ligand/metal ratio vanishes and very good enantioselectivities are achieved at any rate--no matter whether electron-donating or withdrawing substituents are present.     

一种新型双亲性有机小分子催化剂在水相体系中催化环己酮与硝基烯烃直接不对称Michael加成反应

设计合成了一系列基于脯氨酸巯基咪唑衍生物的新型双亲性有机小分子催化剂,在水相中加入酸作为助催化剂,可以高效高选择性的催化环己酮与硝基烯烃的不对称Michael加成反应,非对映选择性和对映选择性分别高达99：1和96%.     

Fluorapatite: efficient catalyst for the Michael addition

A Michael addition assisted by fluorapatite in heterogeneous media is described. Reaction between mercaptans and chalcone derivatives was studied at room temperature in methanol as solvent. By-products of usual undesirable reactions in Michael addition such as 1,2-addition, bis-addition and polymerisation are not observed. The yields obtained are good to excellent.     

Catalyzed double Michael addition of anilines to vinyl sulfone

Substituted anilines and vinyl sulfone undergo a facile double Michael addition to form substituted phenylthiomorpholine dioxide, catalyzed with AlCl₃ or H₃PO₄. Scope and conditions were explored.     

Formamide as an efficient nitrogen nucleophile for the Michael addition to nitroalkenes

Secondary acyclic formamide serves as an efficient nucleophile to nitroalkenes to give corresponding Michael adducts in good yields. The nitro group in the adducts was useful for further heterocyclic synthesis.     

Efficient catalytic aza-Michael additions of carbamates to enones: revisited dual activation of hard nucleophiles and soft electrophiles by InCl3/TMSCl catalyst system

The aza-Michael reaction of a variety of chalcones with weaker nucleophilic carbamates catalyzed by InCl₃ in the presence of TMSCl via the entry of dual activation of both hard nucleophiles (carbamates) and soft electrophiles (enones) to provide the corresponding adducts in good yields. The first example of enantioselective aza-Michael reaction of chalcones with carbamates was also investigated in the presence of the present catalyst system.     

Solvent-free Brønsted acid-catalyzed Michael addition of nitrogen- and carbon-containing nucleophiles by ultrasound activation

A new method has been developed for the Michael addition of nitrogen- and carbon-containing nucleophiles to cyclic enones. Using this conjugate addition reaction, a variety of different nucleophiles can react with a range of cyclic enones in the presence of p-toluenesulfonic acid under solvent-free ultrasound irradiation conditions affording the corresponding C–N or C–C adducts in good to excellent yields. Comparatively, performing the reaction under ultrasound irradiation gives higher yields, is more efficient and environmentally benign than performing it at high pressure.