Synthesis of various camphor-based chiral pyridine derivatives

(+)-β-Hydroxymethylenecamphor 1 and enamines 2a-e were transformed into chiral camphor-based pyridine derivatives 3a-e via a tandem condensation reaction in good yields.     

An efficient synthesis of 7-hydroxy-2,6-dimethylchromeno[3,4-d]oxazol-4-one—a protected fragment of novenamine

The high-yielding six-step synthesis of 7-hydroxy-2,6-dimethylchromeno[3,4-d]oxazol-4-one 17 from commercially available 2,4-dihydroxy-3-methylacetophenone is described. Coumarin 17 constitutes a useful synthon for coumarin antibiotic synthesis. A new methodology for oxazole formation applicable to 3-aminocoumarins has been developed, and a mechanistic rationalization is proposed.     

Activation of Pyridinium Salts for Electrophilic Acylation: a Method for Conversion of Pyridines into 3-Acylpyridines

Cyanide adducts of N-MOM pyridinium salts react with strong acylating reagents to provide 3-acyl-4-cyano-1,4-dihydropyridines that can be aromatized to 3-acylpyridines using ZnCl₂ in refluxing ethanol.     

Stereoselective routes to substituted β-amino carbonyl compounds via heterodiene [4π+2π] cycloadditions of auxiliary-based C2 symmetric ketene acetals

Heterodiene [4π+2π] cycloadditions of (S,S)-4,5-diaryl-2-methylene-1,3-dioxolanes 1 to a series of β-amido-α,β-unsaturated carbonyl compounds are diastereoselective (d.r.≥4:1). The products can be purified by trituration or crystallisation and hydrolysed with acid to generate the corresponding β-amido carbonyl compounds, the overall sequence effecting an auxiliary-based enantioselective conjugate addition of an acetate enolate, leading to β-aminoacid derivatives.     

一个新的铀（Ⅵ）三元协萃体系

研究了由４，４＇－癸二酰－双－（１－苯基－３－甲基－５－吡唑啉酮）（ＤＢＰＭＰ，简作Ｈ２Ａ），氧化三辛基膦（ＴＯＰＯ），吡啶（Ｐｙ）组成的三元体系从硝酸溶液中对铀的协同萃取，斜率法确定萃合物组成为ＵＯ２Ａ．ＴＯＰＯ．Ｐｙ，制取了固体协萃配合物，并用元素分析、ＩＲ及ＨＮＭＲ等进行了表征。     

Propanal in the Syntheses of Alkyl-substituted 3-Cyano-2-piperidone, 3-Cyano-2,5,6,7-tetrahydropyrindin-2(1H)-one, and 3-Cyanopyridine-2(1H)-thione

Condensation of propanal with cyanothioacetamide and morpholine gave 3-cyano-4-ethyl-5-methyl-6-morpholino-2-piperidone, the structure of which was studied by X-ray analysis. Reaction of propanal with cyanothioacetamides and cycloalkanone enamines gave 3-cyano-4-ethyl-2,5,6,7-tetrahydropyrindin-2(1H)-one and 3-cyano-4-ethyl-5,6-hexamethylenepyridine-2(1H)-thione. The latter was used for the preparation of substituted 2-benzyloxycarbonylmethylthiopyridine and 3-amino-2-benzyloxycarbonylthieno[2,3-b]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1053–1059, July, 2005.     

用新型AP树脂分离铑—铱和同时富集测定铑`铱`铂`钯

铑-铱分离-向被认为是最困难的课题之一,即使文献曾报道Rh-Ir的分离,但实际Rh并未与萃取剂或吸附剂反应,而是与非贵金属离子一同留在溶液中。我们曾用光谱半定量方法研究了AP树脂对Rh、Ir的吸附行为,结果是Rh不被吸附而Ir能被吸附。本文通过改变Rh的离子状态,使之能被AP树脂吸附完全,而与留在溶液中的非贵金属分离,然后在柱上用不同淋洗液再使Rh-Ir分离。     

PS-b-P4VP两嵌段共聚物的合成及其自组装的研究

双硫酯 (PhC(S)SCH2 Ph)作为链转移剂 ,AIBN作为引发剂 ,用可逆的加成 断裂链转移 (RAFT)活性自由基聚合方法 ,合成了PS大分子链转移剂 .然后在AIBN引发下 ,利用制得的大分子链转移剂 ,以DMF为溶剂 ,80℃下采用RAFT方法 ,合成了PS b P4VP两嵌段共聚物 ,通过核磁共振谱及动力学的研究证明了其活性聚合的特征 .结果表明聚合反应在 2 4h内转化率可达 95 % .并用透射电子显微镜 (TEM )和扫描电子显微镜(SEM)研究了PS b P4VP两嵌段共聚物在选择性溶剂硝基苯 四氢呋喃中的自组装行为 ,研究结果表明改变聚合物的浓度以及选择性溶剂 ,可观察到自组装行为的变化 .     

Reduction of 2,5-di-tert-butylcyclopentadienone and pyridine with thulium diiodide. Structures of the complexes TmI2(THF)2[η5-But2C5H2O]TmI2(THF)3 and [TmI2(C5H5N)4]2(μ2-N2C10H10)

Reduction of 2,5-di-tert-butylcyclopentadienone with two equivalents of thulium diiodide in tetrahydrofuran afforded the binuclear thulium(iii) complex with the cyclopentadienyl oxide ligand, viz., TmI₂(THF)₂[⁵-Bu^t ₂C₅H₂O]TmI₂(THF)₃ (1). Shielding of the carbonyl carbon atom with two tert-butyl substituents prevents pinacolization of the ketyl radical anions that formed upon one-electron reduction of cyclopentadienone. The reaction of thulium diiodide with an excess of pyridine in tetrahydrofuran gave a product of reductive coupling of two pyridine radical anions, viz., [TmI₂(C₅H₅N)₄]₂(₂-N₂C₁₀H₁₀) (2). The structures of complexes 1 and 2 were established by single-crystal X-ray diffraction analysis.