Efficient access to 5-substituted thiazoles by a novel metallotropic rearrangement

A novel rearrangement process involving the migration of trimethylstannanyl or trimethylsilanyl groups around the thiazole ring provides access to either 2- or 5-metallated thiazoles by tuning the reaction conditions. The proposed mechanism, based on experimental evidence, is characterized by the catalytic role of thiazole bisadducts as metal-transfer agents.     

Simple and Efficient Procedure for Highly Diastereoselective Synthesis of trans- 1,1-Disubstituted-2,6-diarylcyclohexane-4-ones

A simple and efficient method has been developed for highly diastcreoselective synthesis of trans-1,1-disubstituted-2,6-diarylcyclohexane-4-ones from dibenzalacetone and malononitril with trans-1,2-diaminocyclohexane as catalyst. The substrate 1,5-diaryl-1,4-pentadien-3-ones and active methylene compounds proceeded to give the products with good to excellent yield within a short time.     

肟和环戊二烯杂Diels-Alder反应的理论计算

应用量子化学中的密度泛函（B3LYP/6-311G(d,p)）和二级微扰（MP2/6-311G(d,p)）方法对肟和环戊二烯的杂Diels-Alder反应机理进行了计算.结果表明,碳氮键先于碳碳键生成,碳氮键和碳碳键的生成与断裂属非同步的协同过程,C=O键在反应中钝化,不参与反应;反应符合前线轨道理论,利于反应进行;从热力学和动力学角度分析,此反应可以进行,优化计算的结果意义较大;反应计算数据与已有实验结果一致.     

Base induced cyclobutenone rearrangements and its application in the synthesis of aromatic amines

A series of fully substituted 2-pyridone 2 and functionalized α-pyrones 3 are synthesized starting from cyclobutenones 1 under a base-promoter in toluene at 80 °C. This rearrangement is complimentary to the previously reported ring expansion of cyclobutenones, providing a divergent synthesis of corresponding products from the same precursor 1. In addition, α-pyrones 3 has also been applied to the synthesis of aromatic amines 7 in good yields (64–83%) and in a highly regioselective manner via D-A reaction under mild conditions.     

4-芳氨基取代喹啉的13C NMR研究

报道了16种新的4-芳氨基取代喹啉的¹³C NMR谱.应用¹³C NMR等谱确定了这16种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

High density polyethylene/hydrogenated oligo(cyclopentadiene) blends: Tensile stress-strain behavior

The influence of hydrogenated olio(cyclopentadiene) (HOCP) on tensile mechanical properties of its blends with high density polyethylene (HDPE) has been studied at 20, 80, and 100°C. The nominal stress-strain curves performed at 20°C indicate an increase of the modulus and a conspicuous decrease of the ultimate properties increasing the HOCP content in the blend. Blends with HOCP content > 20%-wt are found to be very fragile at 20°C. These behaviors have been related to the presence of the HOCP-rich phase that has the glass transition at about 55°C. At 20°C the HOCP oligomers act as a hardener for the HDPE. The nominal stress-strain curves performed at 80 and 100°C show a strong decrease of the modulus (compared to the value at 20°C), plastic deformation for all the blends tested, and rupture of HDPE and blend samples at the beginning of the cold-drawing. Moreover, the modulus and the ultimate parameters are found to decrease with the composition. The behaviors at 80 and 100°C have been related to several factors: the higher mobility of HDPE molecules at these temperatures compared to that at 20°C; the HOCP-rich phase that is at temperatures higher than its glass transition, and so it acts as a plasticizer for the HDPE; and the decreases of crystallinity and number of entanglements when the HOCP is added to the HDPE component. ©1995 John Wiley & Sons, Inc.     

Theoretische Untersuchungen zur Molekülstruktur und Spektroskopie von Benzopyrylium-Verbindungen: Vollständig-optimierte S0- und S1-Molekülgeometrien des 5,6-Dihydrobenzo[c]xanthylium-Ions und Einfluß der Strukturfixierung sowie Substitution auf sein elektronisches Spektralverhalten in Absorption und Fluoreszenz

Summary Completely-optimized S₀ and S₁ molecular geometries of 5,6-dihydrobenzo[c]xanthylium ion are presented. Using these structural results the influence of structural fixation and of substitution on its spectral behaviour in absorption and fluorescence is studied theoretically and compared with experimental data.

     

Gold-catalyzed heteroannulation and allyl migration: synthesis of highly functionalized indole derivatives

Highly substituted indole derivatives have been prepared in good to excellent yields by a novel gold-catalyzed cyclization accompanied by [3,3]-migration of the allyl strategy. We have been able to introduce an allyl group at the C1 position of pyrano[3,2-e]indol-6(7H)-one and pyrrolo[3,2-f]quinolin-7(6H)-one moieties that provide a scope for further transformation.