CeCl_3·7H_2O as an efficient catalyst for one-pot synthesis of β-amino ketones by three-component Mannich reaction

Cerium trichloride heptahydrate(CeCl_3·7H_2O) was found to be an efficient and recyclable catalyst for the three-component direct Mannich reaction of anilines and benzaldehydes with acetophenone.This protocol has advantages of high yield,no environmental pollution,mild condition,and simple work-up procedure.

Amide Ionic Liquids(AILs)/L-Proline Synergistic Catalyzed Asymmetric Mannich Reactions

Amide ionic liquids （MLs）/L-proline synergistic catalyzed Mannich reactions of isovaleraldehyde, methyl ketones, and aromatic amines were carried out in moderate to high yields （ up to 96% ） and high stereo selectivities （ 〉99% e. e. ）. The products were easily isolated by extraction; and the catalyst system was readily recycled at least thrice without significant loss of efficiency. The scope of the substrates was studied and the interpretation of the manifest improvement of the reaction rates and enantio-selectivity of the novel catalyst system was speculated.

A New Investigation of Mannich Reaction

During the synthesis of the derivatives of styryl ketonic Mannich bases, a side -product IM,other than the normal Mannich base MA, is obtained. Mannich reaction is further studied and the formation mechanism of product IM is postulated and discussed on the basis of deuterium labelling.

Theoretical Studies on the Mechanism of Mannich Reaction Involving Iminium Salt as Potential Mannich Reagent(1)--Use Acetaldehyde as Pseudo-acid Component

This paper is one of a series of reports of theoretical researches on the mechanism of the Mannich reaction using the iminium salt as the potential Mannich reagent. According to the results of AM1 dynamic calculations, the activation energies of key steps in conventional Mannich reactions between ammonia, formaldehyde and acetaldehyde in neutral and acidic media are 438 8 kJ/mol and 393 9 kJ/mol respectively. The activation energy of the rate controlling step of the Mannich reaction which contains the potential Mannich reagent is 274 7 kJ/mol. Therefore, it can be derived that the potential Mannich reagent can increase the rate of the reaction remarkably. The reasons for this have been discussed in terms of the orbital match and electrostatic interaction between the atoms of reactant complexes. In this paper another different conjectured mechanism of the potential Mannich reagent which can reduce the activation energy is considerably studied.

Synthesis and Crystal Structure of the Derivative of Hydroquinone from Mannich Reaction

The regioselective Mannich-type aminomethylation of hydroquinone afforded a nitrogen-containing compound, 2,5-bis-(morpholinomethyl)hydroquinone A, and its crystal structure was determined by single-crystal X-ray diffraction. Crystal data for A: C16H24N2O4, Mr = 308.37, orthorhombic, space group Pbca, a = 10.479(4), b = 10.298(4), c = 14.865(5) ?, V = 1604.3(11) ?3, Z = 4, Dc = 1.277 g/cm3, F(000) = 664, μ = 0.092 mm-1, GOF = 1.078, the final R = 0.0508 and wR = 0.1075 for 1416 observed reflections with I > 2σ(I). There exist two intramolecular O–H…N hy- drogen bonds between the phenolic O atoms and the morpholine N donors and the morpholino rings assume the preferred chair conformation.

Stereoselectivities in α- and β-Amino Acids Catalyzed Mannich Reactions Involving Cyclohexanone

The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory.Transition states of the stereo-determining C ＂C bond-forming step with the addition of enamine intermediate to the imine for the L-proline（·-amino acid） and （R）-3-pyrrolidinecarboxylic acid（·-amino acid）-catalyzed processes were reported.B3LYP/6-31G calculations provide a good explanation for the opposite syn vs.anti diastereoselectivities of these two different kinds of catalysts（syn-selectivity for the ·-amino acid catalysts,anti-selectivity for the ·-amino acid catalysts）.Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.

Effect of Polyethyleneimine Assisting the Growth of Eu-doped ZnO Nanowire Arrays in Mannich Reaction

In study on the growth reaction mechanism of Eu-doped ZnO nanowire（NW）, the intermedium of reaction is characterized by measures such as FTIR. Besides, the influences of polyethyleneimine（PEI） on morphology, structure and photoelectric property of NW are observed by SEM, TEM, XRD, UV-vis and PL spectrum. According to the result, it manifests that Eu-doped ZnO NW array growth response experiences six mutually associated reaction processes in PEI-HMTA system：（a） chelation reaction of PEI and Zn^2＋ ＆ Eu^3＋;（b） protonation reaction of PEI and NH_3;（c） decomposition reaction of hexamethylenetetramine（HMTA）;（d） Mannich reaction of HCHO and PEI;（e） formation of precursor of Eu-doped ZnO;（f） dehydration condensation of Eu-doped ZnO precursors, further forming a doped ZnO NW array. Among them, PEI is the key factor of the whole doping growth reaction process. It both plays a role in modifying the growth of ZnO NW and makes it become longer and thinner. In the meantime, it also facilitates doping of Eu and enables ZnO NW to capture more photoelectrons and higher transmission rate, which is critical to improve photovoltaic performance of optoelectronic devices.

A New One-Pot Synthesis of Macroheterocycles Using Mannich Reaction

Three N,N-heterylmethyl derivates of diaza-18-crown-6(I) are readily prepared by the reaction of (I) with paraformaldehyde and heterocyclic compounds in dry benzene.

基于苯磺酸和2,2′-联吡啶双配体的锰配合物的结构及其催化Mannich反应性能和机理

由溶剂热法合成了2个锰的超分子配合物[Mn_(2)(2,2'-bipy)_(4)(H_(2)O)Cl_(3)](L_1)·6H_(2)O (1)和[Mn(2,2'-bipy)_(2)(H_(2)O)Cl](L_(2))·3H_(2)O (2)(L_(1)^(-)=对甲基苯磺酸根,L_(2)^(-)=间硝基苯磺酸根,2,2'-bipy=2,2'-联吡啶),并用单晶X射线衍射、红外光谱、热重分析和氮气吸附-脱附测试对其进行了表征。以Mannich反应为探针,研究了2种配合物的催化性能,并通过对比2种配合物的扫描电镜和粉末X射线衍射表征结果,分析了配合物结构对其催化性能的影响。最后通过密度泛函理论预测了配合物的活性位点,利用X射线光电子能谱证明了活性位点的活化作用,进而阐述了配合物催化Mannich反应的机理。

苯磺酸锰配合物的制备及其催化Mannich反应性能研究

以氯化锰与苯磺酸钠为原料,通过加热合成了苯磺酸锰,进一步将溶剂挥发,得到了苯磺酸锰配合物.通过单晶X-射线衍射技术测定了晶体结构,分子式为:[Mn(H_(2)O)_(6)](C_(6)H_(5)SO_(3))2.粉末X-射线衍射证明目标产物具有较高的相纯度.红外光谱法验证了目标产物的分子结构.热重分析方法表明目标产物的热稳定性较好,在510℃前未分解.实验使用Mannich反应作为探针,考察了苯磺酸锰配合物的催化性能,结果表明,该配合物在催化Mannich反应时,用量少,效率高,重复使用三次仍保持催化活性,苯磺酸锰配合物催化性能良好.

酒石酸衍生的双羟基手性磷酸催化不对称Mannich-type反应

设计合成了数种由天然酒石酸衍生的双羟基手性磷酸,并考察了其对不对称Mannich-type反应的催化性能.结果发现:设计合成的双羟基手性磷酸可以高效催化该反应,并显示中等至良好的对映选择性(高达91%ee).

Isosteviol-amino Acid Conjugates as Highly Efficient Organocatalysts for the Asymmetric One-pot Three-component Mannich Reactions

Isosteviol-amino acid conjugates were synthesized and used as chiral catalysts for the asymmetric three-component Mannich reaction with hydroxyacetone as donor molecule. Good yields （up to 98%） and excellent stereoselectivities （up to 97 ： 3 dr and 99% ee） were achieved in a short reaction time. In addition, syn- or anti-configurations of a-hydroxy-β-amino carbonyl compounds were obtained as main products with different chiral catalysts.

Sulfonated poly(4-vinylpyridine) heteropolyacid salts:A reusable green solid catalyst for Mannich reaction

Sulfonated poly（4-vinylpyridine） heteropolyacid salts acted as a heterogeneous catalyst to effectively catalyze the one-pot synthesis of β-amino carbonyl compounds via the Mannich reaction between aromatic aldehydes, aromatic ketone, and aromatic amines. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity.

PEG-OSO_3H as an efficient and recyclable catalyst for the synthesis of β-amino carbonyl compounds via the Mannich reaction in PEG-H_2O

Sulfuric acid-modified polyethylene glycol 6000（PEG-OSO_3H） was applied as an efficient and recyclable catalyst for the synthesis ofβ-amino carbonyl compounds via the Mannich reaction between aldehydes,aromatic ketones and aromatic amines at room temperature using PEG400-H_2O（1：1） as environment-friendly solvents.The reactions were completed in short times and mild reaction conditions with good to excellent yields.

One-pot Three-component Mannich Reaction Catalyzed by 2-Hydroxylpyridine

An effcient synthetic protocol for the β-amino carbonyl compounds was developed via one-pot three- component Mannich reaction of aromatic aldehydes, aromatic amines and cyclohexanone catalyzed by 2-hydroxylpy- ridine under mild reaction conditions, β-Amino carbonyl compounds were obtained in moderate to good yields and rea- sonable diastereoselectivities. The effects of different solvents, catalyst amounts and the scope of different substrates on the Mannich reactions were investigated. The plausible reaction mechanism was also discussed.

Scope and Limitations of Optical Pure Hydantoins as Chiral Auxiliaries in Asymmetric Mannich Reactions

The Mannich reaction of various 5-substituted and N-acyl substituted chiral hydantoins with a series of aldimines smoothly occurred with full stereochemical control. These Mannich adducts have been cleaved by alcoholysis to afford several synthetically useful chiral building blocks like β-amino esters and β-lactams in good yields and in enantiopure form.

Cross double Mannich reaction catalyzed by I_2:Synthesis of highly substituted 4-piperidones

Cross double Mannich reaction and tandem cyclization were achieved under iodine catalyzed conditions,yielding a series of highly substituted 4-piperidones.Among the possible diastereomers,only one diastereomer was isolated,which could be ascribed to the chair-like transition state in six-membered ring,in which all of the hindered groups are located in the pseudoequatorial orientation.

Synthesis,Characterization and Application of Some Axially Chiral Binaphthyl Phosphoric Acids in Asymmetric Mannich Reaction

Two novel chiral Brønsted acids 3b and 3c were prepared without involving the complexity of Suzuki coupling.Catalyst 3c bearing two additional hydroxyl groups at 3 and 3'positions of axially chiral 1,1-binaphthalene-2,2'-diol phosphoric acid was applied in a model Mannich reaction to affordβ-amino ester in high yield(92%)and enantiomeric excess(91%)at low reacting temperature of−40℃.In addition,thoseβ-amino ester derivatives with high yields and excellent enatioselectivities were obtained in the presence of catalyst 3c under the above condition.

Chiral Phase-transfer Catalysts Bearing Multiple Hydrogen-bonding Donors Derived from Amino Acids： Efficient Catalysts for Diastereo- and Enantioselective Nitro-Mannich Reaction

The asymmetric nitro-Mannich reaction is one of the traditional methods for forming carbon-carbon bond. By this reaction, the corresponding products with two contiguous stereocenters containing nitrogen substituents can be obtained. These β-nitro amine products can be easily transformed into 1,2-diamines by reduction of the corresponding nitro groups by means of the Nef reaction. It is well known that chiral 1,2-diamines Nay an important role in many fields.

Highly efficient synthesis of β-amino esters via Mannich-type reaction under solvent-free conditions using ZnCl_2 catalyst

β-Amino esters were synthesized via ZnCl2-catalyzed Mannich-type reaction of imines and malonate esters under solvent-free conditions in 6 min. The β-amino ester was converted into the corresponding aspartic acid derivatives.