Industrial Chemical - Carbon Disulphide Manufacturer …
Asymmetric Total Syntheses of Colchicine, β …
Subsequently, the proposed transition-metal-catalyzed decarbonylation/electrocyclic ring-opening cascade reaction of 3 was attempted using several different catalysts (Rh, Ni, and Pd) in a variety of different solvents, as reported previously. However, these conditions failed to afford any of the desired product of 2. To our delight, the irradiation of a solution of β-lumicolchicine (3) in 10:1 (v/v) CH3CN/acetone (0.0024 mol/L) with a 125 W high-pressure mercury arc lamp surrounded by a Pyrex water jacket for 20 min gave 2 in 54% yield instead of α-lumicolchicine (4) and colchicine. The outcome of this transformation suggested that under the irradiation compound 3 had probably undergone a decarbonylation process to generate the intermediate B, followed by the anticipated retro-4π-electrocyclization reaction to give 2, which has been reported to exhibit greater inhibitory activity toward tubulin than colchicine. The 1H and 13C NMR spectra of synthetic 2 and 3, as well as their optical rotation, were identical to those of the natural products. We also have tried to extend the time of irradiation for one-pot synthesis of compound 2 from 1, but a trace of 2 was detected. Probably, other unidentified compounds made the reaction more complex, with the time extended and the temperature of the solution increased. So, after many attempts, we found that 25 min is the best time length for the first irradiation and the two-step sequence is more efficient than the one-pot procedure for the preparation of 2 from 1.
Owing to their unusual structural motifs and promising pharmacological properties, colchicine (1) and NCME (2) have attracted considerable attention from synthetic chemists, which has resulted in several elegant total syntheses of 1 and 2. Recently, we developed an enantioselective synthesis of colchicine (1) from commercially available and inexpensive 2,3,4-trimethoxybenzaldehyde (5). The challenging tricyclic 6–7–7 core of colchicinoids was efficiently introduced using an intramolecular oxidopyrylium-mediated [5 + 2] cycloaddition reaction. In our continuing efforts toward the synthesis of biologically active natural products, we herein describe a modified concise and highly enantioselective synthesis of colchicine using the Wacker oxidation for the regioselective construction of the highly oxidized tropolone C-ring. Moreover, asymmetric total syntheses of β-lumicolchicine and NCME were also achieved.
May « 2017 « New Drug Approvals
ABSTRACT: The chemistry of β-lactams has taken an prestigious place in organic and medicinal chemistry so the review on recent methods in the synthesis of 2-Azetidinone derivatives rendered as a lead molecule for designing potential bioactive agents and it accompanying additional various synthetic information and its orientations would encompass great deal of help to researchers, chemists and pharmacologists to make it the best, most productive, economical and medicinal important compounds which will be expected to show potent pharmacological activities. In future it would be useful to design different new drugs to bring in the market by using rapid, operationally simple, efficient and green procedure. This has led to the discovery of a wide variety of compounds that are of high interest from the point of view antibacterial, anti-inflammatory, antihyperlipidemic, CNS activity, anticancer, antimicrobial, pesticidal, cytotoxic, antidiabetic, antitumor, antifungal, antitubercular activities.
Colchicine (1), which is an alkaloid natural product, was the first tubulin-destabilizing agent to be reported in the literature (). This material has also been investigated against a variety of different indications because of its remarkable antimitotic activity. Furthermore, in a similar manner to many other tubulin-binding natural products (e.g., taxol and the epothilones), colchicine has been used to treat several diseases, including acute gout and familial Mediterranean fever. Colchicine has also been used as a neurotoxin in animal models of Alzheimer’s disease and epilepsy, as well as to treat chronic myelocytic leukemia. However, its high toxicity has precluded its clinical use in cancer chemotherapy. Interestingly, some of the allocolchicines including -acetylcolchinol--methyl ether (NCME) (2), which are biphenyl analogues of colchicine, have been found to be active against various cancer cell lines, including drug-resistant ones. They operate by inhibiting tubulin assembly and polymerization, leading to the arrest of cell mitosis.
PDF Downloads : Oriental Journal of Chemistry
Nikalje et al53 reported the reaction of the synthesis of N’-(substituted- aryl/heterylidene) isonicotinohydrazide1 (a-j) were prepared by reaction between equimolar quantities of isoniazid and substituted aldehydes in ethanol. A mixture of Schiff base 1 and chloroacetyl chloride in dimethylformamide was taken inErlenmeyer flask. Triethyl amine was added to the reaction mixture, as a catalyst. The mixture was irradiated in microwave oven to give N-(3-chloro-2-oxo-4-substitutedazetidin-1- yl) isonicotinamide(2a-j)
Patel et al 45 reported a series of novel azetidinones 5a-i have been synthesized by cyclocondensation of various Schiff bases of coumarin with chloro acetyl chloride in presence of triethyl amine. The reaction of 4-hydroxy coumarin with POCl3 yielded 4-chloro coumarin 2 and 4-chloro-3, 4', 3', 4"-tercoumarin 2a. Compound 2 was reacted with p-phenylenediamine to yield 4-[(4-aminophenyl)amino]-2H-chromen-2-one. Various Schiff bases of coumarin were synthesized by condensation of 4-[(4-aminophenyl)amino]-2H- chromen-2-one with different aldehydes
Statutes & Constitution :View Statutes : Online Sunshine
Register of designated Orphan Medicinal Products (by …
Synthesis - Home - Michigan State University
Preparation of Ester Derivatives of Fatty Acids for Chromatographic Analysis The following was first published by W.W
Thus the 4-methyl-2-pentanone ..
nucleophilic attack of an aryl metal reagent derived from 2-bromo-para ..
A wholly owned subsidiary Qidong Accela ChemBio Co
Parmar et al 40 reported series of novel 2-Azetidinones (8a-h) have been synthesized by cyclocondensation of various Schiff bases based of ATT with chloroacetyl chloride in presences of triethylamine. Various Schiff bases were synthesized by condensation of ATT with various aryl aldehydes (7a-h). The synthesized compounds 8a-h was screened for their antibacterial activity.
2-Bromo-4-methyl-3-pentanone: C6H11BrO: 29583-93-5:
Taj et al 34 reported an efficient green approach to the synthesis of Schiff bases (11–21) of 1-amino-2-aryl-3-oxo-1, 2, 4- triazoles (1–3) under Mg(ClO4)2 as catalyst followed by the reaction with chloroacetyl chloride in solvent-free conditions to yield the azetidinones (22–32) with excellent yields. The synthesized compounds were evaluated for the extent of penetration into biological membranes (clogP), drug-likeliness and finally drug score was calculated and also screened for antitubercular and antimicrobial activities.
ethyl 2-methyl butyrate, 7452-79-1 - The Good Scents …
Taj et al 54 reported an efficient green approach to the synthesis of Schiff bases (11–21) of 1-amino-2-aryl-3-oxo-1,2,4- triazoles (1–3) under Mg(ClO4)2 as catalyst followed by the reaction with chloroacetyl chloride in solvent-free conditions to yield the azetidinones (22–32) with excellent yields. The synthesized compounds were evaluated for the extent of penetration into biological membranes (clogP), drug-likeliness and finally drug score was calculated and also screened for antitubercular and antimicrobial activities.
Recommendation for ethyl 2-methyl ..
Sahoo et al 32 synthesized some novel 2-azetidinone derivatives. 3-bromo-4-methoxybenzoyl hydrazine was prepared from methyl ester of 4-methoxybenzoic acid by bromination and subsequent hydrazinolysis. The acid hydrazide was condensed with different aromatic aldehydes in ethanol as solvent to yield substituted benzal-3-(3’-bromo-4’-methoxybenzoyl) hydrazines. The benzalhydrazines on cyclization with phenoxyacetyl chloride in presence of triethylamine as catalyst afforded 3-phenoxy-4-(substituted phenyl)-1-(3’-bromo-4’-methoxy benzamide)azetidin-2-ones.
"I have always been impressed by the quick turnaround and your thoroughness. Easily the most professional essay writing service on the web."
"Your assistance and the first class service is much appreciated. My essay reads so well and without your help I'm sure I would have been marked down again on grammar and syntax."
"Thanks again for your excellent work with my assignments. No doubts you're true experts at what you do and very approachable."
"Very professional, cheap and friendly service. Thanks for writing two important essays for me, I wouldn't have written it myself because of the tight deadline."
"Thanks for your cautious eye, attention to detail and overall superb service. Thanks to you, now I am confident that I can submit my term paper on time."
"Thank you for the GREAT work you have done. Just wanted to tell that I'm very happy with my essay and will get back with more assignments soon."