1779-60-8Relevant articles and documents
Probing the effects of microwave irradiation on enzyme-catalysed organic transformations: The case of lipase-catalysed transesterification reactions
Leadbeater, Nicholas E.,Stencel, Lauren M.,Wood, Eric C.
, p. 1052 - 1055 (2007)
The lipase-catalysed transesterification reaction of methyl acetoacetate in toluene as a solvent has been studied using carefully controlled conditions. Results suggest that microwave heating does not have a noticeable effect on reaction rate or product conversion. This journal is The Royal Society of Chemistry.
Synthesis, study of 3D structures, and pharmacological activities of lipophilic nitroimidazolyl-1,4-dihydropyridines as calcium channel antagonist
Miri, Ramin,Javidnia, Katayoun,Sarkarzadeh, Hasti,Hemmateenejad, Bahram
, p. 4842 - 4849 (2006)
QSAR studies indicated that the potency of nifedipine analogues was dependent upon lipophilicity, an electronic term and separated terms for each position on the DHP ring. Changes in the substitution pattern at the C3, C4, and C5 positions of DHPs alter potency, tissue selectivity, and the conformation of the 1,4-DHP ring. In this project a group of alkyl ester analogues of new derivatives of nifedipine, in which the ortho-nitrophenyl group at position 4 is replaced by a 1-methyl-5-nitro-2-imidazolyl substituent, and the methyl group at position 6 is replaced by a phenyl substituent, were synthesized and evaluated as calcium channel antagonist using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle. The results for asymmetrical esters showed that lengthening of the substituent in C3 ester substituent increased activity. When increasing of the length is accompanied by increasing the hindrance, the activity decreased. The results demonstrate that all compounds were more active or similar in effect to that of the reference drug nifedipine.
Synthesis and evaluation of pharmacological activities of 3,5-dialkyl 1,4-dihydro-2,6-dimethyl-4-nitroimidazole-3,5-pyridine dicarboxylates
Miri, Ramin,Javidnia,Kebriaie-Zadeh,Niknahad,Shaygani,Semnanian,Shafiee
, p. 422 - 428 (2003)
New analogues of nifedipine, in which the 2-nitrophenyl group at position 4 is replaced by a 1 -methyl-5-nitro-2-imidazolyl substituent, were synthesized. The symmetrical dialkyl 1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-2-imidazolyl)-3, 5-pyridinedicarboxylates were prepared by a classical Hantzsch condensation. The asymmetrical analogues were synthesized using a procedure reported by Iwanami that involved the condensation of alkylacetoacetate with methyl-, ethyl- or isopropyl-3-aminocrotonate and 1 -methyl-5-nitroimidazole-2-carboxaldehyde. Calcium channel antagonist activities were determined in vitro using a guinea pig ileum longitudinal smooth muscle (GPILSM) assay. Many compounds exhibited superior, or equipotent, calcium antagonist activity (IC50 = 10- 10 to 10-13 M range) relative to the reference drug nifedipine (IC50 = 1.09? 0.12 × 10-11 M). Antinociceptive effects of some compounds were evaluated by the mouse tail-flick assay in vivo. Results demonstrate that some of the compounds were active as an antinociceptive.
Br?nsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols
Naikwadi, Dhanaji R.,Singh, Amravati S.,Biradar, Ankush V.
, (2021/10/04)
Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ～1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ～100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.
N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters
Chityala, Yadaiah,Duguta, Govardhan,Kamatala, Chinna Rajanna,Muddam, Bhooshan,Mukka, Satish Kumar
supporting information, p. 1641 - 1655 (2020/05/25)
N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack (VH) adducts with 1,3,5-triazine compunds such as trichloroisocyanuric acid (TCCA) and trichlorotriazine (TCTA) were prepared by replacing classical oxy chlorides POCl3, and SOCl2, which were explored as efficient catalysts for the transesterification of β-ketoesters. The prepared (TCCA/DMF) and (TCTA/DMF) adducts improved greenery of the classical Vilsmeier–Haack reagents (POCl3/DMF), and (SOCl2/DMF), and demonstrated their better efficient catalytic ativity. Reaction times were in the range: 3.5 to 6.5 hr (SOCl2/DMF); 2.8–5.2 hr (POCl3/DMF); 2.5–5.2 hr (TCCA/DMF) and 2.5–5.0 hr (TCTA/DMF) catalytic systems. Ultrasonically (US) assisted protocols with these reagents further reduced the reaction times (two to three times), while microwave assisted (MW) protocols with these reagents were much more effective. The reactions could be completed in only few seconds (less than a minute) in MWassisted protocols as compared to US assited reactions, followed by good product yields.
COMPOSITIONS COMPRISING A POLYMERIC NETWORK
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Paragraph 0528, (2017/12/15)
The present invention relates to a composition comprising a polymeric network having at least one unit of formula (I), (II), and/or (III); (I) (II) (III) wherein said composition is obtained by contacting at least one compound A comprising at least two functions selected from the group of function of formula X—C(═O)—CHR1—C(═O)—R2, —C(═O)—C—R2; or —C(═O)—CR1═CR2—NR4R5; wherein at least 25% by weight of compounds A have a functionality ≦5, with % by weight relative to the total weight of compounds A; with at least one compound B comprising at least one NH2, or NH3+ groups; wherein X, R1, R2, R3, R4, R5, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to a compound comprising at least two units and at most 5 units of formula (I), (II), and/or (III); wherein R1, R2, R3, X, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to processes for preparing said composition and said compounds, to material, articles, and polymers comprising or using said compositions and compounds, and the use thereof.
Ag-Cu nanoparticles as efficient catalysts for transesterification of β-keto esters under acid/base-free conditions
Yue, Hongmei,Yu, Hao,Liu, Sheng,Xu, Chunli
, p. 19041 - 19051 (2016/03/01)
Transesterification of β-keto esters and alcohols are traditionally catalyzed by acid or basic catalysts. However, these traditional catalysts do not always meet the requirements of modern synthetic chemistry which need to be highly efficient, selective, and environmentally friendly. In this work, Ag-Cu metal sites were first introduced as transesterification catalysts. The effect of the support, Ag:Cu molar ratio, and reaction conditions were investigated. The Ag-Cu metal sites were proved to be active in the β-ketoester transesterification with various alcohols, having yields comparable to the conventional acid- or base-catalysts.
Copper-catalyzed radical coupling of 1,3-dicarbonyl compounds with terminal alkenes for the synthesis of tetracarbonyl compounds
Zhang, Mei-Na,Zhao, Mi-Na,Chen, Ming,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
supporting information, p. 6127 - 6130 (2016/05/19)
A novel and efficient copper-catalyzed radical cross-coupling of 1,3-dicarbonyl compounds with terminal alkenes for the synthesis of tetracarbonyl compounds with a quaternary carbon atom has been developed. Mechanistically, this transformation involves the construction of two C-C bonds and two CO bonds in a one-pot process. The reaction tolerates a wide range of functional groups and proceeds under mild conditions.
Vinylogous urethane vitrimers
Denissen, Wim,Winne, Johan M.,Du Prez, Filip E.,Rivero, Guadalupe,Nicola, Renaud,Leibler, Ludwik
, p. 2451 - 2457 (2015/09/08)
Vitrimers are a new class of polymeric materials with very attractive properties, since they can be reworked to any shape while being at the same time permanently cross-linked. As an alternative to the use of transesterification chemistry, we explore catalyst-free transamination of vinylogous urethanes as an exchange reaction for vitrimers. First, a kinetic study on model compounds reveals the occurrence of transamination of vinylogous urethanes in a good temperature window without side reactions. Next, poly(vinylogous urethane) networks with a storage modulus of ≈2.4 GPa and a glass transition temperature above 80 °C are prepared by bulk polymerization of cyclohexane dimethanol bisacetoacetate, m-xylylene diamine, and tris(2-aminoethyl)amine. The vitrimer nature of these networks is examined by solubility, stress-relaxation, and creep experiments. Relaxation times as short as 85 s at 170 °C are observed without making use of any catalyst. In addition, the networks are recyclable up to four times by consecutive grinding/compression molding cycles without significant mechanical or chemical degradation. Catalyst-free vitrimers based on the transamination of vinylogous urethanes are prepared from readily accessible chemicals. These high Tg, cross-linked materials exhibit excellent mechanical properties, while the exchangeable bonds enable full stress-relaxation on short time scales and recycling over many cycles.
Prussian blue as an efficient catalyst for rate accelerations in the transesterification of β-ketoesters
Srinivas,Rajanna,Krishnaiah,Kumar, M. Satish,Reddy, J. Narender
, p. 1212 - 1220 (2014/04/17)
Prussian blue triggered transesterification of ethylacetoacetate with various alcohols underwent efficiently. The reaction is mild, eco-friendly, and selective with good yields. The proposed reaction pathway depicts the formation of an intermediate by the interaction of β-ketoesters with catalytic site of the Prussian blue, followed by nucleophilic attack of the alcohol at the electrophilic center followed by successive elimination of the proton to give the product. Observed longer reaction times under conventional conditions reduced amazingly under sonication and microwave irradiation followed enhanced yield of products.
