Silica Sulfuric Acid: A Versatile and Reusable Catalyst for Synthesis of Coumarin-3-carboxylic Acids in a Solventless System

Synthesis of substituted coumarin-3-carboxylic acid via Knoevenagel condensation of meldrum's acid with ortho-hydroxyaryl aldehydes in solventless system is described.     

Stereoselective total synthesis of (−)-zeylenol,a key intermediate for the synthesis of (+)-pipoxide, (−)-uvarigranol G and (−)-tonkinenin A

Total synthesis of (?)-zeylenol, a key intermediate for the synthesis of (+)-pipoxide, (?)-uvarigranol G and (?)-tonkinenin A was achieved from commercially available starting material d-mannose. The key steps are mixed aldol condensation, Grignard reaction, ring closing metathesis and regioselective benzoylation.     

Highly efficient AgNO3‐catalyzed approach to 2‐(benzo[d]azol‐2‐yl)phenols from salicylaldehydes with 2‐aminothiophenol, 2‐aminophenol and benzene‐1,2‐diamine

A new, convenient and efficient AgNO₃‐catalyzed strategy for the preparation of 2‐(benzo[d]azol‐2‐yl)phenol derivatives in good to excellent yields (63–98%) is described. The reaction proceeds via condensation/intramolecular nucleophilic addition/oxidation process between substituted salicylaldehydes and 2‐aminothiophenol, 2‐aminophenol or benzene‐1,2‐diamine under mild reaction conditions. Notably, this reaction utilizes cheap AgNO₃ as a readily available and low‐cost benign oxidant at low catalyst loadings with excellent functional group tolerance.     

A new class of stereoregular vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain

A synthesis of a new macromolecular class of vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain is presented. Two transition‐metal‐catalyzed processes, which is silylative‐coupling copolycondensation (SCC) and ADMET copolymerization of divinyl‐substituted double‐decker silsesquioxanes (DDSQ‐2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ‐silylene‐vinylene‐arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1044–1055     

CONDENSATION REACTION OF 1-OXO-4-CHLOROCARBONYL-1-PHOSPHA-2,6,7-TRIOXABICYCLO[2.2.2]OCTANE WITH N-t-BUTYL-N-BENZOYLHYDRAZINE

Abstract

1-Oxo-4-chlorocarbony1-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane (5) was obtained from phosphorus oxychloride. Benzyl chloroformate was synthesized by the reaction of benzyl alcohol and triphosgene in good yield for the first time. N-r-Butyl-N-benzoylhydrazine(II) was prepared in a new and convenivent procedure with good yield. The reaction of 5 and II proceeded smoothly in the presence of sodium carbonate and afforded the desired compound 13 in good yield, while in the presence of triethylamine, the elimination of butyl was observed and afforded the compound 12.     

REACTIVITY AND STEREOSELECTIVITY IN THE DIELS-ALDER REACTIONS BETWEEN CYCLOPENTADIENE AND SOME α, β-UNSATURATED THIOESTERS

Abstract

Some new norbornene thioester derivatives of endo configuration are sinthesized. Proofs are provided that thioester group has more preference for endo configuration than the ester group.     

Hydrolysis-Condensation Kinetics of Different Silane Coupling Agents

Abstract

The hydrolysis kinetics of 14 alkoxy silane coupling agents were carried out in an ethanol:water 80:20 (w/w) solution under acidic conditions and were monitored by ¹H, ¹³C, and ²⁹Si NMR spectroscopy. Acidic conditions were selected in order to enhance the silanol formation and to slow down the self-condensation between the resulting hydrolysed silanol groups. In situ ²⁹Si NMR spectroscopy allowed the determination of the intermediate species as a function of the reaction time. Thus, the following silane coupling agents were studied: 3-methacryloxypropyl trimethoxy silane (MPMS), 3-mercaptopropyl trimethoxy silane (MRPMS), 3-cyanopropyl triethoxy silane (CPES), triethoxy vinyl silane (VES), trimethoxy (2-phenylethyl) silane (PEMS), octyl triethoxy silane (OES), trimethoxy (7-octen-1-yl) silane (OEMS), 3-aminopropyl triethoxy silane (APES), 3-aminopropyl trimethoxy silane (APMS), 3-(2-aminoethylamino)propyl trimethoxy silane, (DAMS), 3-[2-(2-aminoethylamino)-ethylamino]propyl trimethoxy silane (TAMS), 4-amino-3,3-dibutyl trimethoxy silane (ADBMS), trimethoxy [3-(phenylamino)propyl] silane (PAPMS), and triethoxy-3-(2-imidazolin-1-yl) propyl silane (IZPES). A parameter quantifying the grafting potentiality of each silane coupling agent towards OH-rich solid substrates (such as cellulose) was established as a function of the nature of the alkoxy groups (methoxy or ethoxy), as well as that of the fourth substituent (vinyl, aminopropyl, etc.) of the silane studied.

GRAPHICAL ABSTRACT     

Room-Temperature Bismuth-Catalyzed Bis-arylation of Carbonyl Compounds with Aryl Ethers and Phenols

Using Bi2（SO4）3 as the catalyst and TMSCl as the additive, a wide variety of aldehydes, ketones, and acetals were smoothly condensed with aryl ethers at room temperature to provide the corresponding diarylmethanes and triarylmethanes selectively in good to excellent yields.     

基于5-(2-羧基苯基)吡啶-3-甲酸配体的镍(Ⅱ)和锌(Ⅱ)配位聚合物的合成、晶体结构、催化及抗磨性质

采用水热方法,选用5-(2-羧基苯基)吡啶-3-甲酸配体(H₂cpna)与1,2-二(4-吡啶基)乙烷(dpea)或1,2-二(4-吡啶基)乙烯(dpey)分别与NiCl₂·6H₂O和ZnCl₂在160℃下反应,合成了2个三维配位聚合物{[Ni(μ₃-cpna)(μ-dpea)_0.5]·H₂O}_n (1)和{[Zn(μ₃-cpna)(μ-dpey)_0.5]·H₂O}_n (2),并对其结构、催化和摩擦性质进行了研究。研究表明,在室温条件下化合物2在Knoevenagel缩合反应中显示出较好的催化活性。同时,2在聚α-烯烃合成润滑剂中显示出有效的抗磨性能。     

膦酰肽和膦酰酯肽的汇聚式合成

本文首先介绍了膦酰肽的分类、结构特征以及膦酰肽的主要合成方法,然后详细介绍了类Mannich反应在合成氨基膦酸衍生物中的应用,并介绍了以类Mannich反应为关键步骤通过汇聚式的方法合成膦酰肽、膦酰酯肽、次膦酰肽、次膦酰酯肽、磺酰膦酰杂交肽的研究进展.汇聚式的合成方法具有原料简单、合成步骤少、原子经济性好等优点.