- N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters
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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.
- Chityala, Yadaiah,Duguta, Govardhan,Kamatala, Chinna Rajanna,Muddam, Bhooshan,Mukka, Satish Kumar
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supporting information
p. 1641 - 1655
(2020/05/25)
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- Design, synthesis, and bioactivity of dihydropyrimidine derivatives as kinesin spindle protein inhibitors
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A series of twenty-one 3,4-dihydropyrimidine derivatives bearing the heterocyclic 1,3-benzodioxole at position 4 in addition to different substituents at positions 2, 3 and 5 were designed and synthesized as monastrol analogs. The novel synthesized compounds were screened for their cytotoxic activity towards 60 cancer cell lines according to NCI (USA) protocol. Compounds 10b and 15 showed the best antitumor activity against most cell lines. Compound 15 was subsequently tested in 5-doses mode and displayed high selectivity towards CNS, prostate and leukemia subpanel with selectivity ratios of 22.30, 15.38 and 12.56, respectively at GI50 level. The IC50 of compounds 9d, 10b, 12, 15 and 16 against kinesin enzyme were 3.86 ± 0.12, 10.70 ± 0.35, 3.95 ± 0.12, 4.36 ± 0.14, and 14.07 ± 0.45 μM respectively, while the prototype compound, monastrol, reported IC50 value of 20 ± 0.42 μM. The safest compound among test compounds against normal cell line (HEK 293) is 10b with IC50 value of 62.02 ± 2.42 μM/ml in comparison to doxorubicin (IC50 = 11.34 ± 0.44 μM/ml). Cell cycle analysis of SNB-75 cells treated with compound 15 showed cell cycle arrest at G2/M phase. Further, the assay of levels of active caspase-3 and caspase-9 was investigated. Moreover, Molecular docking of compounds, 9d, 10b, 12, 15, 16, monastrol and mon-97 was performed to study the interaction between inhibitors and the kinesin spindle protein allosteric binding site.
- Tawfik, Haytham O.,El-Hamamsy, Mervat H.,Sharafeldin, Nabaweya A.,El-Moselhy, Tarek F.
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- A synthetic method of an m-nisoldipine medicine intermediate isobutyl acetoacetate
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A synthetic method of an m-nisoldipine medicine intermediate isobutyl acetoacetate is disclosed. The method includes adding 10.6 mol of methyl iso-butyl ether and 3-3.2 mol of methylamine into a reactor provided with a stirrer, a thermometer, a reflux condenser and a dropping funnel, controlling the stirring speed to be 160-190 rpm, raising the temperature of the solution to 85-90 DEG C, adding dropwise 10.6-10.8 mol of diketene (2) while maintaining the reaction temperature to be 85-88 DEG C with the addition time being controlled to be 4-5 h, refluxing for 4 h after the addition is finished with the reaction solution being brown, cooling the solution until the temperature of the solution is 35-40 DEG C, washing with a salt solution, dehydrating with a dehydrating agent, performing vacuum distillation, and collecting a distillate at 109-115 DEG C to obtain the isobutyl acetoacetate (1). The mass percentage of the methylamine is 65-70%.
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Paragraph 0014; 0015
(2016/11/17)
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- Prussian blue as an efficient catalyst for rate accelerations in the transesterification of β-ketoesters
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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.
- Srinivas,Rajanna,Krishnaiah,Kumar, M. Satish,Reddy, J. Narender
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p. 1212 - 1220
(2014/04/17)
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- General and efficient transesterification of β-keto esters with various alcohols using Et3N as a br?nsted base additive
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Transesterification of β-keto esters with a wide variety of allyl, benzyl, propargyl, and alkyl alcohols using, for the first time, commercially available and inexpensive Et3N as a Br?nsted base additive, is efficiently performed in toluene at reflux. The corresponding esters are exclusively obtained in 57-98% yields with no trace amounts of γ,δ-ketones, usually expected from the decarboxylative Carroll rearrangement.
- Mhasni, Olfa,Erray, Imen,Rezgui, Farhat
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p. 3320 - 3327
(2015/10/06)
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- An efficient synthesis of β-ketoesters via transesterification and its application in Biginelli reaction under solvent-free, catalyst-free conditions
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A simple and efficient transesterification process for the synthesis of β-ketoester derivatives has been achieved by the reaction of methyl β-ketoester with higher alcohols at 110 C under solvent-free, catalyst-free conditions and its application in synthesis of 3,4-dihydropyrimidin-2(1H)-ones C-5 ester derivatives via Biginelli reaction has been described.
- Dharma Rao,Acharya,Kaushik
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supporting information
p. 6644 - 6647
(2013/11/19)
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- Manganese(II) salts as efficient catalysts for chemo selective transesterification of β-keto esters under non-conventional conditions
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Transesterification of β-ketoesters with various alcohols has been studied under conventional and non-conventional conditions using desktop chemicals such as Mn(II) salts as catalysts. These methods offered transesterification of β-ketoesters in good yields with dramatic rate accelerations and reduced reaction times. The developed protocols under nonconventional methods such as sonication and microwave irradiation are highly promising compared with the existing procedures.
- Krishnaiah,Sandeep,Kondhare,Rajanna,Narendar Reddy,Rajeshwar Rao,Zhubaidha
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p. 703 - 706
(2013/02/23)
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- AgOTf-catalyzed transesterification of β-keto esters
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AgOTf proved to be an effective catalyst for the transesterification of β-keto esters with primary, secondary and tertiary alcohols. The products were obtained in high yield within a reasonable reaction time period. The kinetics of the transesterification reaction were also studied and the reaction was found to follow second-order kinetics. Copyright
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 140 - 144
(2012/05/20)
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- Design and synthesis of new 1,4-dihydropyridines containing 4(5)-chloro-5(4)-imidazolyl substituent as a novel calcium channel blocker
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New analogues of nifedipine, in which the ortho-nitro phenyl group at position 4 has been replaced by 4(5)-chloro-5(4)-imidazolyl substituent and which are able to interact with the receptor by hydrogen binding were designed, synthesized, and evaluated as calcium channel antagonists. The designed dihydropyridines were synthesized using the Hantzsch condensation and evaluated as calcium channel antagonists using the high K+ contraction of guineapig ileal longitudinal smooth muscle. A docking study was performed using the AutoDock4 program, and QSAR equations were obtained using multilinear regression. Our computational studies indicated that the oxygen of the ester (O10) and the N3′ of the imidazole ring form a hydrogen bonding interaction with the NH of HIS 363 and NH of LYS354, respectively, and that the sum of the BEHp5 and RDF075p are the most significant descriptors. The results of calcium channel antagonist evaluation demonstrated that increasing the chain length in C3 and C5 ester substituents increased activity. The most potent compound was the bis-phenylpropyl ester (5l) derivative, in that it was more active than the reference drug nifedipine and that the bis-phenylethyl ester (5k) derivative had comparable activity with nifedipine. The present research revealed that the 4(5)-chloro-5(4)-imidazolyl moiety is a bioisoster of o-nitrophenyl in nifedipine and provided novel dihydropyridines with more activity as calcium channel antagonists.
- Iman, Maryam,Davood, Asghar,Nematollahi, Ali Reza,Dehpoor, Ahmad Rerza,Shafiee, Abbas
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experimental part
p. 1417 - 1426
(2012/05/04)
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- Efficient trans-acetoacylation mediated by ytterbium(III) triflate as a catalyst under solvent-free condition
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A simple and efficient trans-acetoacylation method for the synthesis of β-keto ester derivatives has been described using ytterbium(III) triflate as a new catalyst under solvent-free condition. This method was found to be efficient and convenient for the synthesis of a wide variety of β-keto ester derivatives.
- Dharma Rao,Kaushik
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experimental part
p. 5104 - 5106
(2011/10/08)
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- BF3OEt2: An efficient catalyst for transesterification of β-ketoesters
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A facile and selective transesterification of β-ketoesters using BF3OEt2 as catalyst is described. The emphasis has been placed on the reaction of methyl acetoacetate with a series of alcohols of different structures, leading in all cases to good to excellent yields.
- Yang, Jinhui,Ji, Congbin,Zhao, Yanmin,Li, Yunfeng,Jiang, Shizhi,Zhang, Zhiwei,Ji, Yongqiang,Liu, Wanyi
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experimental part
p. 957 - 963
(2010/06/12)
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- Ligand-dependent mechanistic dichotomy in iron-catalyzed allylic substitutions: σ-allyl versus π-allyl mechanism
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(Chemical Equation Presented) Iron at the crossroads: A remarkable mechanistic dichotomy in iron-catalyzed allylic substition increases not only the scope of regioselective allylic alkylation but could also herald the development of asymmetric allylic substitution (see Scheme, MTBE = methyl tert-butyl ether). Depending on the ligand used, either a σ-or a π-allyl mechanism is observed.
- Plietker, Bernd,Dieskau, Andre,Moews, Katrin,Jatsch, Anja
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p. 198 - 201
(2008/09/20)
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- Boric acid: an efficient and environmentally benign catalyst for transesterification of ethyl acetoacetate
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An efficient and environmentally benign boric acid catalyzed protocol for the transesterification of ethyl acetoacetate with a variety of primary and secondary alcohols in good to excellent yields is described. The versatility of this transformation is demonstrated with problematic substrates such as propargyl alcohol and allyl alcohol, which are known to undergo Carroll rearrangement during transesterification.
- Kondaiah,Reddy, L. Amarnath,Babu, K. Srihari,Gurav,Huge,Bandichhor,Reddy, P. Pratap,Bhattacharya,Anand, R. Vijaya
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p. 106 - 109
(2008/04/13)
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- Microwave assisted rapid and efficient synthesis of aryl methyl ketones and β-keto esters using Meldrum's acid
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Microwave mediated rapid and efficient synthesis of aryl methyl ketones and β-keto esters from acyl Meldrum's acid by hydrolysis and alcoholysis, respectively, has been reported.
- More,Mahulikar
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p. 823 - 825
(2007/10/03)
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- Synthesis, study of 3D structures, and pharmacological activities of lipophilic nitroimidazolyl-1,4-dihydropyridines as calcium channel antagonist
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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.
- Miri, Ramin,Javidnia, Katayoun,Sarkarzadeh, Hasti,Hemmateenejad, Bahram
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p. 4842 - 4849
(2007/10/03)
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- Synthesis and evaluation of pharmacological activities of 3,5-dialkyl 1,4-dihydro-2,6-dimethyl-4-nitroimidazole-3,5-pyridine dicarboxylates
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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.
- Miri, Ramin,Javidnia,Kebriaie-Zadeh,Niknahad,Shaygani,Semnanian,Shafiee
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p. 422 - 428
(2007/10/03)
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- Zinc mediated transesterification of β-ketoesters and coumarin synthesis
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The transesterification of ketoesters using zinc and iodine is described. The reaction has been done on a variety of alcohols and phenols. Alcohols furnish transesterified products whereas phenols gave 4-methylcoumarins. The method is highly promising compared with existing methods.
- Chavan, Subhash P,Shivasankar,Sivappa,Kale, Ramesh
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p. 8583 - 8586
(2007/10/03)
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- Solid-phase synthesis of pyrrolo[3,4-b]pyridines and related pyridine- fused heterocycles
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Sequential Hantzsch condensation and cyclative cleavage reactions have been used to define a novel solid-phase route to pyrrolo[3,4-b]pyridines and related pyridine-fused heterocycles. A combinatorial library of ~5000 compounds prepared via this chemistry is described.
- Bhandari, Ashok,Li, Bei,Gallop, Mark A.
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p. 1951 - 1960
(2007/10/03)
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- Asymmetric N-(3,3-diphenylpropyl)aminoalkyl esters of 4-aryl-2,6- dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acids with antihypertensive activity
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A series of asymmetric 4-aryl-1,4-dihydropyridine-3,5-dicarboxylates characterized by the presence of a 3,3-diphenylpropylamino moiety in one of the ester groups were synthesized. They exhibited remarkable antihypertensive activity in spontaneously hypertensive rats as well as affinity for the 1,4- dihydropyridines binding site labelled by 3H-nitrendipine in the calcium channel. Introduction of this bulky and lipophilic amine confers to the whole series an elevated level of antihypertensive activity and a long duration of action, a structure-dependent modulation of the activity being found only in the subset characterized by the presence of a branched propylene bridge between the ester and the amino groups. The presence of the amino group is essential for oral activity. Out of this series, compound 9u (Rec 15/2375- lercanidipine) was selected for clinical development and obtained marketing authorization as an antihypertensive in several countries.
- Leonardi, Amedeo,Motta, Gianni,Pennini, Renzo,Testa, Rodolfo,Sironi, Giorgio,Catto, Alberto,Cerri, Alberto,Zappa, Marco,Bianchi, Giorgio,Nardi, Dante
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p. 399 - 420
(2007/10/03)
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- Synthesis and calcium-channel antagonist activity of 4-imidazolyl-1,4-dihydropyridines
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The o-nitrophenyl group at position 4 of dihydropyridine of nifedipine analogues was replaced by 1-methylimidazole. These compounds were evaluated as calcium-channel antagonists using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle. The results for the symmetrical esters showed that increasing the length of methylene chain of ester more than 3 units decreases activity. For cyclic esters, cyclopropylmethyl ester was more active than cyclohexylmethyl ester. Our results revealed two compounds with activities similar to the reference drug nifedipine; the symmetrical cyclopropylmethyl ester, and the asymmetrical phenethyl ethyl derivatives were the most potent antagonists tested.
- Pourmorad,Hadizadeh,Shafiee
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p. 165 - 168
(2007/10/03)
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- Spirolactones from Dirhodium(II)-Catalyzed Diazo Decomposition with Regioselective Carbon-Hydrogen Insertion
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Dirhodium(II) caprolactamate, Rh2(cap)4, catalyzes diazo decomposition of cycloalkylmethyl diazoacetates which form spirolactones in moderate to high yield by insertion into a tertiary carbon-hydrogen bond.Similar results are obtained with diazoacetates derived from tetrahydropyran-2-methanol and tetrahydrofurfuryl alcohol but not from cyclopropylmethanol.With tetrahydrofuran-3-ylmethyl diazoacetate, Rh2(cap)4 catalysis promotes δ-lactone formation via insertion into the oxygen-activated secondary C-H bond instead of γ-lactone formation by carbene insertion into the unactivated tertiary C-H bond.However, when both 1,5- and 1,6-positions are activated for insertion by adjacent oxygen atoms, as in (2,2-dimethyl-1,3-dioxolan-4-yl)methyl diazoacetate, five-membered ring formation occurs exclusively in Rh2(cap)4-catalyzed reactions, whereas use of dirhodium(II) acetate leads to both insertion products.
- Doyle, Michael P.,Dyatkin, Alexey B.
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p. 3035 - 3038
(2007/10/02)
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