Synthesis of Substituted Pyrroles via Ultrasound Assisted Three—com—ponent Coulling Reaction of Amines,α，β—Unsaturated Aldehydes and Nitroalkanes

An efficient synthesis of substituted pyrroles via ultrasound-assisted three-component coupling reaction of amines with α，β-unsaturated aldehydes and nitroalkanes is reported.     

Synthesis,structure, and urease inhibitory activities of Co(III), Mn(II) and Zn(II) complexes with hydrazone derived from protocatechuic acid

[Co^III(L₁)₂·H₂O]NO₃ (1), [Mn^II(L₁)₂·H₂O] (2), and [Zn^II(L₁)₂·H₂O] (3) with a hydrazone derived from protocatechuic acid (HL₁ = C₁₅H₁₃N₃O₃) were designed, synthesized, and characterized by C, H, N elemental analyses, single-crystal X-ray diffraction, and IR spectra, which revealed that the three complexes are similar structures. Docking study has been done. The urease inhibitory activities of the three complexes were tested. Complexes 1 and 3 showed strong inhibitory activity against jack bean urease with IC₅₀ values of 45.9 and 11.64 μM. Complex 2 had no obvious inhibitory activity to urease; the IC₅₀ was > 50 μM.     

DFT mechanistic study on nickel/IPr-catalyzed aldehyde–alkyne reductive couplings with trialkylsilane/dialkylsilane

Density functional theory calculations were carried out to reveal the mechanistic details of aldehyde–alkyne reductive couplings with trialkylsilane/dialkylsilane. The reaction with trialkylsilane is found to proceed through oxidative cyclization, Si-H/Ni-O σ-bond metathesis, and C(sp²)-H reductive elimination, leading to silylated allylic alcohols. The steric hindrance between the n-pent group of alkyne and iPr group of the NHC ligand determines the regioselectivity. While for the reaction with dialkylsilane, the present calculations propose a new mechanism, which consists of oxidative cyclization, Si−H/Ni−O σ-bond metathesis, Ni−C/Si−H σ-bond metathesis, and dehydrogenation, resulting in oxasilacyclopentenes. The calculated energy profiles rationalize the experimentally observed chemodivergence.     

A generalised route for the synthesis of β-furyl-α,β-unsaturated aldehydes through Suzuki reactions

A general method for the synthesis of β-(2-furyl)-α,β-unsaturated aldehydes is described using the Suzuki coupling reaction of furan-2-boronic acids and β-bromo-α,β-unsaturated aldehyde derivatives.     

N-(4-苯基-噻唑-2-基)芳醛腙类化合物的合成

以芳醛与氨基硫脲进行缩合得到缩氨基硫脲, 分别与ω-溴苯乙酮进行成环反应得到了一系列含噻唑环和芳基的腙类化合物, 并通过用¹H NMR、质谱、红外光谱等对化合物进行了结构表征.     

烯丙基转移反应合成直链高烯丙基醇

研究了不同脂肪族和芳香族醛与6-甲基-6-苯基-7-烯-1,5-辛二醇的烯丙基转移反应, 同时考察了溶剂对反应的影响. 结果发现, 在In(OTf)3催化下, 以甲苯为溶剂, 由脂肪族醛合成的直链高烯丙基醇较芳香族醛具有较高的产率和较好的选择性, 所得产物结构经1H NMR, 13C NMR, IR, HRMS表征.     

Enantioselective direct vinylogous Michael addition reaction catalyzed by organic molecules

Chiral 2-azanorbornyl-3-methanol is used as an organocatalyst for the highly enantioselective direct vinylogous Michael addition reaction of vinyl malononitriles to α,β-unsaturated aldehydes. In many cases, the products can be obtained in almost optically pure form (>95% ee) after a single recrystallization.     

Synthesis of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes Using Yb(OTf)3 as an Efficient Catalyst under Solvent‐free Conditions

A series of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes were prepared under solvent‐free conditions by Yb(OTf)₃ catalyzed condensation reactions of β‐naphthol with various aldehydes. The process presented here is operationally simple, environmentally benign and has good to excellent yields. Furthermore, the catalyst can be recovered conveniently and reused efficiently.     

Catalysis by L-Lysine:A Green Method for the Condensation of Aromatic Aldehydes with Acidic Methylene Compounds in Water at Room Temperature

The condensation of aromatic aldehydes with acidic methylene compounds such as ethyl benzoylacetate, 2,4‐pentanedione and dimedone proceeded efficiently in pure water in the presence of L‐lysine at room temperature. Interestingly, there are two different reaction mechanisms taking place under the same green catalyst system. This provides a green and mild synthetic method for the preparation of these two classes of compounds.     

Miktoarm star copolymers via combination of RAFT arm‐first technique and aldehyde–aminooxy click reaction

A facile synthetic pathway to miktoarm star copolymers with multiple arms has been developed by combining reversible addition–fragmentation chain transfer (RAFT) arm‐first technique and aldehyde–aminooxy “click” coupling reaction. Star polystyrene (PS) with aldehyde functionalized core was initially prepared by RAFT arm‐first technique via crosslinking of the preformed linear macro‐RAFT agents using a newly designed aldehyde‐containing divinyl compound 6,6′‐(ethane‐1,2‐diylbis(oxy))bis(3‐vinylbenzaldehyde) (EVBA). It was then used as a multifunctional coupling agent for the subsequent formation of the second generation poly(ethylene glycol) (PEG) arms via the click coupling reaction between its aldehyde groups and aminooxy‐terminated PEGs. The possible formation of PS‐PEG miktoarm star copolymer with Janus‐like segregated structure in cyclohexanone was also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3323–3330, 2010