نتایج جستجو برای: knoevenagel

تعداد نتایج: 502  

Journal: :Organic & biomolecular chemistry 2015
Carole Guyon Marie-Christine Duclos Marc Sutter Estelle Métay Marc Lemaire

A one-pot two-step reaction (Knoevenagel condensation - reduction of the double bond) has been developed using calcium hydride as a reductant in the presence of a supported noble metal catalyst. The reaction between carbonyl compounds and active methylene compounds such as methylcyanoacetate, 1,3-dimethylbarbituric acid, dimedone and the more challenging dimethylmalonate, affords the correspond...

Journal: :journal of nanostructures 2015
b. f. mirjalili a. bamoniri s. m. nezamalhosseini

the knoevenagel condensation of aromatic aldehydes with barbituric acid, dimedone and malononitrile occurred in the presence of bf3/nano-γ-al2o3 at room temperature in ethanol. this catalyst is characterized by powder x-ray diffraction (xrd), fourier transform infrared spectroscopy (ft-ir), thermal gravimetric analysis (tga), field emission scanning electron microscopy (fesem) and energy-disper...

We present herein a new and efficient four-component synthesis of isoxazol-5(2H)-ones involving ring closing/Knoevenagel condensation/Michael addition sequential reactions.

Aboulghasem Hashemi Ali Khalafi Nezhad

Efficient Knoevenagel condensation of barbituric acid with different aromatic aldehydes on basic alumina was performed in a conventional microwave over in the absence of solvent.

2009
Shi-Jie Zhang Xian-Ming Zheng Wei-Xiao Hu

The title compound, C(12)H(10)N(2)O(6), was synthesized via a Knoevenagel condensation and crystallized from ethanol. In the crystal, strong classical inter-molecular O-H⋯O hydrogen bonds and weak C-H⋯N contacts link the mol-ecules into ribbons extending along [010]. Intra-molecular O-H⋯O and C-H⋯N contacts support the planar conformation of the mol-ecules (mean deivation 0.0270 Å).

Journal: :The Journal of organic chemistry 2004
D B Ramachary K Anebouselvy Naidu S Chowdari Carlos F Barbas

Amino acids and amines have been used to catalyze three component hetero-domino Knoevenagel/Diels-Alder/epimerization reactions of readily available various precursor enones (1a-l), aldehydes (2a-p), and 1,3-indandione (3). The reaction provided excellent yields of highly substituted, symmetrical and nonsymmetrical spiro[cyclohexane-1,2'-indan]-1',3',4-triones (5) in a highly diastereoselective...

2018
Snehali Mali Sachin Shinde Shashikant Damte Suresh Patil

Without using any toxic or hazardous reagent, ligand, acid, transition metal catalyst, additives/promoters and organic solvent, green Knoevenagel condensation and tandem Knoevenagel-Michael reactions have been successfully carried out by using chickpea leaf exudates as a naturally sourced Bronsted acid type bio-catalyst. The reaction proceeds in neat chickpea leaf exudates at room temperature i...

Journal: :Molecules 2017
Yanhui Qiao Junjiang Teng Shuangfei Wang Hao Ma

A biomass-based catalyst with amine groups (-NH₂), viz., amine-functionalized sugarcane bagasse (SCB-NH₂), was prepared through the amination of sugarcane bagasse (SCB) in a two-step process. The physicochemical properties of the catalyst were characterized through FT-IR, elemental analysis, XRD, TG, and SEM-EDX techniques, which confirmed the -NH₂ group was grafted onto SCB successfully. The c...

Journal: :Chemical Science 2023

Covalent organic framework (COF) is an outstanding manifesto for heterogeneous photocatalysis. Herein, we synthesized a pyrene-based two-dimensional C=C linked π-conjugated COF via Knoevenagel condensation and anchored Ni(II)-center through bipyridine moieties....

2013
Shahrzad Abdolmohammadi Saeed Balalaie

A series of pyrido[2,3-d]pyrimidines derivatives have been prepared by one-pot three-component reaction of 4(6)aminouracil, malononitrile and aromatic aldehydes. This efficient synthesis was done under microwave irradiation conditions (method A) and also using catalytic amount of diammonium hydrogen phosphate [(NH4)2HPO4] (DAHP) in aqueous media (method B). This procedure has the advantages of ...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید

function paginate(evt) { url=/search_year_filter/ var term=document.getElementById("search_meta_data").dataset.term pg=parseInt(evt.target.text) var data={ "year":filter_year, "term":term, "pgn":pg } filtered_res=post_and_fetch(data,url) window.scrollTo(0,0); } function update_search_meta(search_meta) { meta_place=document.getElementById("search_meta_data") term=search_meta.term active_pgn=search_meta.pgn num_res=search_meta.num_res num_pages=search_meta.num_pages year=search_meta.year meta_place.dataset.term=term meta_place.dataset.page=active_pgn meta_place.dataset.num_res=num_res meta_place.dataset.num_pages=num_pages meta_place.dataset.year=year document.getElementById("num_result_place").innerHTML=num_res if (year !== "unfilter"){ document.getElementById("year_filter_label").style="display:inline;" document.getElementById("year_filter_place").innerHTML=year }else { document.getElementById("year_filter_label").style="display:none;" document.getElementById("year_filter_place").innerHTML="" } } function update_pagination() { search_meta_place=document.getElementById('search_meta_data') num_pages=search_meta_place.dataset.num_pages; active_pgn=parseInt(search_meta_place.dataset.page); document.getElementById("pgn-ul").innerHTML=""; pgn_html=""; for (i = 1; i <= num_pages; i++){ if (i===active_pgn){ actv="active" }else {actv=""} pgn_li="
  • " +i+ "
  • "; pgn_html+=pgn_li; } document.getElementById("pgn-ul").innerHTML=pgn_html var pgn_links = document.querySelectorAll('.mypgn'); pgn_links.forEach(function(pgn_link) { pgn_link.addEventListener('click', paginate) }) } function post_and_fetch(data,url) { showLoading() xhr = new XMLHttpRequest(); xhr.open('POST', url, true); xhr.setRequestHeader('Content-Type', 'application/json; charset=UTF-8'); xhr.onreadystatechange = function() { if (xhr.readyState === 4 && xhr.status === 200) { var resp = xhr.responseText; resp_json=JSON.parse(resp) resp_place = document.getElementById("search_result_div") resp_place.innerHTML = resp_json['results'] search_meta = resp_json['meta'] update_search_meta(search_meta) update_pagination() hideLoading() } }; xhr.send(JSON.stringify(data)); } function unfilter() { url=/search_year_filter/ var term=document.getElementById("search_meta_data").dataset.term var data={ "year":"unfilter", "term":term, "pgn":1 } filtered_res=post_and_fetch(data,url) } function deactivate_all_bars(){ var yrchart = document.querySelectorAll('.ct-bar'); yrchart.forEach(function(bar) { bar.dataset.active = false bar.style = "stroke:#71a3c5;" }) } year_chart.on("created", function() { var yrchart = document.querySelectorAll('.ct-bar'); yrchart.forEach(function(check) { check.addEventListener('click', checkIndex); }) }); function checkIndex(event) { var yrchart = document.querySelectorAll('.ct-bar'); var year_bar = event.target if (year_bar.dataset.active == "true") { unfilter_res = unfilter() year_bar.dataset.active = false year_bar.style = "stroke:#1d2b3699;" } else { deactivate_all_bars() year_bar.dataset.active = true year_bar.style = "stroke:#e56f6f;" filter_year = chart_data['labels'][Array.from(yrchart).indexOf(year_bar)] url=/search_year_filter/ var term=document.getElementById("search_meta_data").dataset.term var data={ "year":filter_year, "term":term, "pgn":1 } filtered_res=post_and_fetch(data,url) } } function showLoading() { document.getElementById("loading").style.display = "block"; setTimeout(hideLoading, 10000); // 10 seconds } function hideLoading() { document.getElementById("loading").style.display = "none"; } -->