scholarly journals Cyclotrimerization of 3-R-1,2,4-Triazin-5(4H)-ones with Cyclic Ketones

2010 ◽  
Vol 65 (11) ◽  
pp. 1359-1362 ◽  
Author(s):  
Ilya N. Egorov ◽  
Igor S. Kovalev ◽  
Vladimir L. Rusinov ◽  
Oleg N. Chupakhin
Keyword(s):  
Cyclic Ketones ◽  
Acidic Conditions ◽  
Derivatives Of

New heterocyclic tetracyclic systems were synthesized. Interaction between 3-R-1,2,4-triazin- 5(4H)-ones and cyclic ketones under acidic conditions leads to the formation of zwitterion derivatives of 5,6,7,8,9,10,11,12-octahydro-[1,2,4]triazino[1,6- ƒ ]phenanthridine and 1,2,3,6,7,8-hexahydro-bicyclopenta[ b,d]pyrido[1,2- ƒ ][1,2,4]triazine.

scholarly journals Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

2014 ◽  
Vol 10 ◽  
pp. 1919-1932 ◽  
Author(s):  
Mahesh K Lakshman ◽  
Manish K Singh ◽  
Mukesh Kumar ◽  
Raghu Ram Chamala ◽  
Vijayender R Yedulla ◽  
...  
Keyword(s):  
Amide Bond ◽  
Coupling Agents ◽  
Cyclic Ketones ◽  
Substitution Reactions ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
Peptide Coupling ◽  
Acyclic Nucleoside ◽  
Derivatives Of

(1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO− and AtO− produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO− is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd π–allyl complexes by departure of BtO− has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis.

scholarly journals Phenacylation of 6-Methyl-Beta-Nitropyridin-2-Ones and Further Heterocyclization of Products

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1682
Author(s):  
Eugene V. Babaev ◽  
Victor B. Rybakov
Keyword(s):  
Pyridinium Salt ◽  
Phenacyl Bromides ◽  
Acidic Conditions ◽  
Phenacyl Derivatives ◽  
Derivatives Of

Reaction between the derivatives of 6-methyl-beta-nitropyridin-2-one and phenacyl bromides was studied, and the yields observed were extremely low. The pyridones were converted via chloropyridines to methoxyderivatives, which were N-phenacylated. N-Phenacyl derivatives of 4,6-dimethyl-5-nitropyridin-2-one under the action of base gave 5-hydroxy-8-nitroindolizine and under acidic conditions gave 5-methyl-6-nitrooxazole[3,2-a]pyridinium salt, which underwent recycization with MeONa to 5-methoxy-8-nitroindolizine.

Palladium-catalyzed asymmetric hydrogenation of 2-aryl cyclic ketones for the synthesis of trans cycloalkanols through dynamic kinetic resolution under acidic conditions

2020 ◽  
Vol 56 (43) ◽  
pp. 5815-5818 ◽  
Author(s):  
Xiang Li ◽  
Zi-Biao Zhao ◽  
Mu-Wang Chen ◽  
Bo Wu ◽  
Han Wang ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Asymmetric Hydrogenation ◽  
Dynamic Kinetic Resolution ◽  
Cyclic Ketones ◽  
Palladium Catalyzed ◽  
Acidic Conditions

The first efficient palladium-catalyzed asymmetric hydrogenation of 2-aryl cyclic ketones has been described through dynamic kinetic resolution under acidic conditions, providing a facile access to chiral trans cycloalkanols.

Oxyhalogen–sulfur chemistry — Kinetics and mechanism of the bromate oxidation of cysteamine

2008 ◽  
Vol 86 (5) ◽  
pp. 416-425 ◽  
Author(s):  
Moshood K Morakinyo ◽  
Edward Chikwana ◽  
Reuben H Simoyi
Keyword(s):  
Oxidation Product ◽  
Reducing Agent ◽  
Kinetics And Mechanism ◽  
Molecular Bromine ◽  
Sulfur Chemistry ◽  
Diffusion Controlled ◽  
Hypobromous Acid ◽  
Acidic Conditions ◽  
Acid Toxicity ◽  
Derivatives Of

The kinetics and mechanism of the oxidation of the biologically important molecule, cysteamine, by acidic bromate and molecular bromine have been studied. In excess acidic bromate conditions, cysteamine is oxidized to N-brominated derivatives, and in excess cysteamine the oxidation product is taurine according to the following stoichiometry: BrO3– + H2NCH2CH2SH → H2NCH2CH2SO3H + Br–. There is quantitative formation of taurine before N-bromination commences. Excess aqueous bromine oxidizes cysteamine to give dibromotaurine: 5Br2 + H2NCH2CH2SH + 3H2O → Br2NCH2CH2SO3H + 8Br– + 8H+, while excess cysteamine conditions gave monobromotaurine. The oxidation of cysteamine by aqueous bromine is effectively diffusion-controlled all the way to the formation of monobromotaurine. Further formation of dibromotaurine is dependent on acid concentrations, with highly acidic conditions inhibiting further reaction towards formation of dibromotaurine. The formation of the N-brominated derivatives of taurine is reversible, with taurine regenerated in the presence of a reducing agent such as iodide. This feature makes it possible for taurine to moderate hypobromous acid toxicity in the physiological environment.Key words: cysteamine, hypobromous acid, toxicities, antioxidant.

Nitration of 3,4-Dimethylacetophenone and 3,4-Dimethylbenzophenone. Formation and Rearomatization of Adducts

1975 ◽  
Vol 53 (11) ◽  
pp. 1570-1578 ◽  
Author(s):  
Alfred Fischer ◽  
Colin Campbell Greig ◽  
Rolf Röderer
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Nitro Group ◽  
Nitrous Acid ◽  
Main Product ◽  
Intermediate Formation ◽  
Nitro Derivatives ◽  
Acidic Conditions ◽  
Cis And Trans ◽  
Derivatives Of

Nitration of 3,4-dimethylacetophenone in acetic anhydride gives a mixture of cis-and trans-2-acetyl-4,5-dimethyl-4-nitro-1,4-dihydrophenyl acetate as the main product, together with 3,4-dimethyl-2-, 3,4-dimethyl-5-, and 3,4-dimethyl-6-nitroacetophenone. Analogous products are obtained from 3,4-dimethylbenzophenone. Rearomatization of the adducts under mildly acidic conditions occurs via 1,4-elimination of nitrous acid to form 2-acetyl- and 2-benzoyl-4,5-dimethylphenyl acetate, respectively. In strongly acidic conditions elimination of acetic acid accompanied by 1,2- and 1,3-shifts of the nitro group occurs to form the 2- and 5-nitro derivatives of the parent ketones. The rearomatization to the nitro derivatives involves the intermediate formation of an ipso-cyclohexadienyl cation which may be trapped by anisole or mesitylene to form biphenyl derivatives.

Crystallographic and spectroscopic studies of adducts of indium (III) iodide with two cyclic ketones

2000 ◽  
Vol 78 (5) ◽  
pp. 536-541 ◽  
Author(s):  
M A Brown ◽  
D G Tuck
Keyword(s):  
Crystal Structures ◽  
Spectroscopic Studies ◽  
Solution Chemistry ◽  
Cyclic Ketones ◽  
Tetrahedral Structure ◽  
Space Group ◽  
Iodide Solution ◽  
Derivatives Of

Indium(III) iodide forms a 1:1 adduct with 9-xanthenone, of quasi-tetrahedral structure; triclinic, a = 10.805(4), b = 11.494(4), c = 7.493 (2) Å, α = 104.12(3), β = 106.35(3), γ = 91.165(3)°, V = 860.8(5) Å3, Z = 2, space group P1-. With 9-fluorenone, the adduct has 1:2 stoichiometry, and approximately D3h symmetry in the InI3O2 kernel; the structure is triclinic, a =11.212(2), b = 16.504(3), c = 7.537(2) Å, α = 94.57(2), β = 109.05(1), γ = 91.165(15)°, V = 1312.6(4) Å3, Z = 2, space group P1-. The solid structures, and the solution chemistry, are compared with those of related neutral derivatives of indium(III) halides.Key words: Indium(III) iodide, solution chemistry, crystal structures, adducts.

scholarly journals Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

2015 ◽  
Vol 11 ◽  
pp. 1434-1440 ◽  
Author(s):  
Dileep Kumar Singh ◽  
Mahendra Nath
Keyword(s):  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Cycloaddition Reaction ◽  
Spectroscopic Characterization ◽  
Spectroscopic Properties ◽  
Dipolar Cycloaddition ◽  
Free Base ◽  
Acidic Conditions ◽  
Derivatives Of

A novel series of β-triazoloporphyrin–xanthone conjugates and xanthone-bridged β-triazoloporphyrin dyads has been synthesized in moderate to good yields through Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction of copper(II) 2-azido-5,10,15,20-tetraphenylporphyrin or zinc(II) 2-azidomethyl-5,10,15,20-tetraphenylporphyrin with various alkyne derivatives of xanthones in DMF containing CuSO4 and ascorbic acid at 80 °C. Furthermore, these metalloporphyrins underwent demetalation under acidic conditions to afford the corresponding free-base porphyrins in good to excellent yields. After successful spectroscopic characterization, these porphyrins have been evaluated for their photophysical properties. The preliminary results revealed a bathochromic shift in the UV–vis and fluorescence spectra of these porphyrin–xanthone dyads.

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