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1.
A metal‐free approach to benzazoles from arylmethyl chlorides and 2‐mercaptan/2‐hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram‐scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6 , which was characterized by NMR, HRMS and crystal X‐ray crystallography, was separated in the reaction prior to the formation of the product.  相似文献   
2.
The spatial configurations of 7,9-diphenyl-5a,6-tetramethylene-5,5a,6,7-tetrahydropyrido[1,2-a]benzimidazole and 7,9-diphenyl-5a,6-tetramethylene-2,5a,6,7-tetrahydropyrido[1,2-a]benzimidazol-2-one have been established by X-ray crystallography. Analogous configurations are proposed for a series of other derivatives of 5,5a,6,7-tetrahydropyrido[1,2-a]benzimidazoles and some derivatives of 6,7-dihydro-5aH-pyrido[1,2-b]benzoxazoles on the basis of 1H NMR spectroscopic data and the results of quantum chemical calculations using the MNDO, AM1, and PM3 methods.  相似文献   
3.
An efficient synthesis of 2‐substituted benzoxazoles through RuCl3·3H2O catalyzed, air oxidized tandem reactions of 2‐aminophenols and aldehydes in [bmim]BF4 was developed. This synthetic strategy has such advantages as mild reaction conditions, cost‐free oxidant, readily available starting materials, and recyclable catalyst and solvent. As an application, it was successfully used in the synthesis of the unreported 5‐(benzoxazol‐2‐yl)‐2′‐deoxyuridines with potential biological activities.  相似文献   
4.
The base-promoted reaction of 2-halonitro- or 1,2-dihalobenzenes with anthranilamide reported by Cao, Ma et al. (Synthesis 2013 , 45, 111) was reinvestigated. Some of the products reported, which have been identified as dibenzodiazepinones, are actually benzoxazole derivatives. In this paper, the correct structures of these products were established and confirmed by independent synthesis. For four other products, the supposed structures were found to be incompatible with the dibenzodiazepinones that were synthesized by the reliable method used in this work.  相似文献   
5.
A series of poly(o‐hydroxy amide)s having both ether and sulfone linkages in the main chain were synthesized via the low‐temperature solution polycondensation of 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoyl chloride and 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoyl chloride with three bis(o‐aminophenol)s including 4,4′‐diamino‐3,3′‐dihydroxybiphenyl, 3,3′‐diamino‐4,4′‐dihydroxybiphenyl, and 2,2‐bis(3‐diamino‐4‐hydroxyphenyl)hexafluoropropane. Subsequent thermal cyclodehydration of the poly(o‐hydroxy amide)s afforded polyethersulfone benzoxazoles. Most of the poly(o‐hydroxy amide)s were soluble in polar organic solvents such as N‐methyl‐2‐pyrrolidone; however, the polybenzoxazoles without the hexafluoroisopropylidene group were organic‐insoluble. The polybenzoxazoles exhibited glass‐transition temperatures (Tg) in the range of 219–282 °C by DSC and softening temperatures (Ts) of 242–320 °C by thermomechanical analysis. Thermogravimetric analyses indicated that most polybenzoxazoles were stable up to 450 °C in air or nitrogen. The 10% weight loss temperatures were recorded in the ranges of 474–593 °C in air and 478–643 °C in nitrogen. The methyl‐substituted polybenzoxazoles had higher Tg's but lower Ts's and initial decomposition temperatures compared with the corresponding unsubstituted polybenzoxazoles. For a comparative purpose, the synthesis and characterization of a series of sulfonyl polybenzoxazoles without the ether group that derived from 4,4′‐sulfonyldibenzoyl chloride and bis(o‐aminophenol)s were also reported. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2262–2270, 2001  相似文献   
6.
微波辐射下2-芳基取代苯并噁唑的合成   总被引:3,自引:0,他引:3  
邻氨基酚和芳香羧酸在微波辐射条件下缩合,合成了4种2-芳基取代苯并噁唑化合物。优化反应条件为:多聚磷酸为催化剂,辐射功率500W,辐射时间4min。  相似文献   
7.
Jiatao Yu  Yonggen Xia 《合成通讯》2014,44(20):3019-3026
Solvent-free oxidative synthesis of benzimidazoles, benzoxazoles, and benzothiazoles from aromatic primary amines and o-phenylenediamine, o-aminophenol, and o-aminothiophenol has been achieved by using Fe(NO3)3 and TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl). This reaction can use air as an economical and green oxidant, and a wide variety of derivatives were obtained in good to excellent yields. The reaction mechanism was proposed and this method provides a direct, practical, and efficient approach for the preparation of substituted benzimidazoles, benzoxazoles, and benzothiazoles.  相似文献   
8.
Abstract

The synthesis of a salt-free ylid and of a phosphorane obtained by addition of a trivalent phosphorus compound with dimethylacetylene dicarboxylate in the presence of a trapping reagent, benzoic acid is described. This paper is concerned with the first evidence for an ylid-phosphorane equilibrium.  相似文献   
9.
An efficient method for the synthesis of benzoxazoles and benzothiazoles via montmorillonite KSF clay catalyzed condensation reaction between 2-aminophenols or 2-aminothiophenols and β-diketones is reported. The efficiency of the reaction reflects from the wide substrate scope with electronic differentiation on aryls. The reaction is metal free and proceeds without the exclusion of air or moisture, and further the catalyst can be recycled up to 3–5 catalytic cycles.  相似文献   
10.
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