Highly Deoxygenated Sugars. II. Synthesis of Chiral Cyclopentenes via Novel Carbocyclization of C‐4 Branched Deoxysugars

Tri‐O‐acetyl‐d‐glucal (1) was converted via Ferrier type II rearrangement with high α‐selectivity to 2,3‐unsaturated methyl glycosides 2a and 2b using ferric chloride as the catalyst. Palladium induced allylic substitution with sodium tert‐butylacetoacetate as a nucleophile leads to C‐4 branched sugars. Subsequent hydrogenation followed by treatment with trifluoroacetic acid affords the highly functionalized chiral cyclopentene derivative 5a as a versatile chiral building block for cyclopentanoids.     

Catalyst‐Free One‐Pot Synthesis of 2,4,6‐Triaryl‐1,4‐dihydropyridines in Ionic Liquid and Their Catalyzed Activity on Two Simple Diels–Alder Reactions

A series of 2,4,6‐triaryl‐1,4‐dihydropyridines bearing a hydroxyl group was synthesized greenly by the cascade aldol/Michael/addition reaction of aromatic aldehyde, acetophenone, and NH₄OAc (1:2:excessive) in ionic liquid [BmIm][BF₄] without any catalyst. The results of their catalyzed activity on two simple Diels–Alder reactions indicated that this kind of compound containing a poly aryl ring can be used as an effective catalyst on the Diels–Alder reaction. This method, because of its environmental friendliness, simplicity, mild conditions, effectiveness, and lower costs, is suitable for the synthesis of arrays of compounds.     

Practical Synthesis of 1-(7-Fluoro-naphthalen-1-yl)piperazine Hydrochloride

A practical and scalable preparation of 1-(7-fluoronaphthalen-1-yl)-piperazine hydrochloride (1) is reported. The original route for the synthesis of this compound involved the use of 1-amino-7-fluoronaphthalene and bis(2-chloroethyl)amine hydrochloride, two highly toxic compounds. A new protocol has been developed that employs a palladium-catalyzed Buchwald–Hartwig cross-coupling reaction between 1-Boc-piperazine and 1-bromo-7-fluoronaphthalene followed by piperazine deprotection with HCl gas. In addition, an efficient palladium removal protocol allowed for the preparation of the target molecule with less than 20 ppm of this metal. This methodology has been successfully implemented to produce multigram quantities of 1 with excellent purity and low palladium content.     

Synthesis of 4‐(Indol‐1‐yl)butanals via Rhodium‐Catalyzed Hydroformylation of 1‐Allylindoles

The rhodium‐catalyzed hydroformylation of new 1‐(β‐methallyl) indoles 1a–e carried out with Rh₄ (CO)₁₂ as the catalyst precursor, at 100 atm total pressure and 100°C, produces the 4-(indol‐1‐yl)‐3‐methylbutanals 2a–e as the sole products in high yields. The synthesized 4‐indolylbutanals are stable under the adopted conditions and are isolated and characterized here for the first time. The preparation of the starting 1‐allylindoles is described too.     

Gold catalyzed carbocyclization of phenyl substituted allylic acetates to synthesize benzocycle derivatives

An efficient and environmentally benign method was developed to synthesize the benzocycles from phenyl substituted allylic acetates through gold catalyzed Friedel-Crafts type carbocyclization reaction. Different substitution patterns were investigated, which gave a series of benzocyclohexane derivatives in moderate to excellent yields.     

Preparation and property comparison of ortho,meta, and para autocatalytic phthalonitrile compounds with amino group

Phthalonitrile resins with many striking properties have drawn much attention as potential candidates for use in composite matrices, adhesives, films, and electrical conductors for the last 30 years. However, it is common shortcomings for phthalonitrile monomers to have high‐temperature melting point and need extreme conditions to develop binary phthalonitrile/additives composition. Here, three kinds of self‐catalyzed phthalonitrile compounds with low melting point were synthesized, whose structures were characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance. The different cure behaviors, owing to the different positions of catalyzed group on benzene ring, were investigated by differential scanning calorimetry, and cure kinetics parameters were also calculated. The results showed that the meta and para position monomers possessed better reactivity. Melt‐processability study by a rheometer indicated that the ortho one owned the largest processing window. Furthermore, the FTIR spectra demonstrated that the cured monomers contained the same structure with a conventional binary phthalonitrile system. All the cured monomers had excellent thermal stability according to thermogravimetric analysis. Mechanical property was determined by dynamic mechanical analysis, and the results showed that the glass transition temperature (represented by the peak temperature of tanδ) was high up to 550°C for all the three cured monomers. Consequently, these autocatalytic phthalonitrile monomers may be good candidates as matrix for high‐performance polymeric materials. Copyright © 2011 John Wiley & Sons, Ltd.     

催化聚合合成的聚苯乙烯的结构分析

由双-（β-酮苯胺）镍（Ⅱ）／MAO新型催化体系催化聚合制得苯乙烯聚合物,用^1H NMR、^13C NMR、FT—IR、DSC及WAXD等技术对聚合物进行了结构和性能的表征。通过^1H NMR、^13C NMR分析,证实该体系催化聚合得到无规聚苯乙烯（aPS）;DSC结果表明,聚合物的玻璃化温度为Tg=66．6℃;WAXD结果分析表明,所得聚苯乙烯为非晶态,但在较短范围内表现出有序的特征。所有聚合物均可溶于氯仿、2-丁酮、丙酮、甲苯、四氢呋喃、氯苯、邻-二氯苯等有机溶剂中。     

A Copper-Catalyzed [5+1] Cycloaddition of Terminal Alkynes with Diazo Esters through a Tandem 1,5-H-Shift Cyclization

A copper-catalyzed [5+1] cycloaddition reaction of terminal alkynes with diazo esters for the rapid construction of protected naphthalen-1(2H)-one derivatives in moderate to good yields has been disclosed along with good functional group compatibility and a broad substrate scope. The mechanistic investigations reveal that this tandem cyclization process proceeds through a Cu(I)-catalyzed coupling of terminal alkyne with diazoacetate, a 1,5-H shift process and a thermally induced pericyclic reaction via an allene intermediate. The synthetic utility and the further transformations of the obtained cycloadduct to naphthalenone, naphthol and dihydronaphthol have been also presented in this paper.