β-Elimination of a Phosphonate Group from an Alkoxy Radical:  An Intramolecular Acylation Approach Using an Acylphosphonate as a Carbonyl Group Acceptor

2003 ◽  
Vol 125 (32) ◽  
pp. 9574-9575 ◽  
Author(s):  
Sunggak Kim ◽  
Chang Ho Cho ◽  
Chae Jo Lim
Keyword(s):  
Carbonyl Group ◽  
Alkoxy Radical ◽  
Phosphonate Group

Carbanions phosphonate préparés par voie électrochimique: formation et réactivité vis-à-vis d'un aldéhyde

1989 ◽  
Vol 67 (8) ◽  
pp. 1332-1343 ◽  
Author(s):  
Jean-Christophe Le Menn ◽  
Jean Sarrazin ◽  
André Tallec
Keyword(s):  
General Formula ◽  
Carbonyl Group ◽  
Darzens Reaction ◽  
Phosphonate Group ◽  
Mercury Cathode ◽  
Diethyl Phosphate ◽  
Electron Reduction ◽  
Chloride Elimination ◽  
Selection Of

Reactivity towards p-methoxybenzaldehyde (ArCHO) of electrochemically generated phosphonate carbanions has been investigated. Electrolyses were carried out at a mercury cathode in DMF and two routes to the desired carbanion have been compared: (i) Deprotonation of phosphonates of general formula (EtO)2P(O)CHYW (Y = W = Cl; Y = H, W = Cl; Y = Cl, W = CO2Et; Y = H, W = CO2Et; Y = CH3, W = CO2Et; Y = Cl, W = CH3), by the bases resulting from the electroreduction of azobenzene; addition of the carbanion formed onto the carbonyl group takes place and leads to the adduct (EtO)2P(O)CYW(Ar)O−. (ii) Two-electron reduction of halophosphonates (EtO)2P(O)CXYW (X = Cl, Y and W as above; X = Br, W = CO2Et, Y = Cl, Br, or CH3); when no H atom is present on the carbon bearing the phosphonate group (Y and W ≠ H), the same evolution leading to the above adduct is observed; on the contrary, when Y = H, the electrogenerated carbanion deprotonates the substrate and the resulting carbanion [Formula: see text] reacts with the aldehyde, giving the adduct(EtO)2P(O)CXW(Ar)O−.Evolution of the intermediate adduct depends on the substituants Y (or X) and W: when W = CO2Et, whatever the nature of Y (or X), diethyl phosphate is eliminated with formation of the ethylenic ArCH = CWY (or X) (Wittig–Horner reaction); the same evolution is observed when Y = W = Cl. When W = Cl and Y = H or CH3, the final product is the phosphonate epoxyde resulting from chloride elimination (Darzens reaction).Chemo- and stereoselectivity depend only on the nature of Y and W but are independent of the mode of generation of the carbanion. Yields are limited by side-protonation reactions, which are related to the basicity of the phosphonate carbanions. Analysis of the results permits selection of the optimal electrolysis conditions for purposes of synthesis. Keywords: electrosynthesis, electrogenerated bases, phosphonates, Wittig–Horner.

β Elimination of a phosphonate group from an alkoxyl radical — Intramolecular acylation using acylphosphonate derivatives as carbonyl group acceptors

2005 ◽  
Vol 83 (6-7) ◽  
pp. 917-921 ◽  
Author(s):  
Chang Ho Cho ◽  
Sunggak Kim
Keyword(s):  
Carbonyl Group ◽  
Direct Reduction ◽  
Catalytic Amount ◽  
Radical Cyclization ◽  
Alkoxyl Radical ◽  
Phosphonate Group ◽  
Radical Acceptor ◽  
Ready Access ◽  
First Time ◽  
Cyclohexanone Derivative

The possibility of β elimination of a phosphonate group in radical reactions was studied. The facile β elimination of the phosphonate group from an alkoxyl radical was observed for the first time, whereas the β elimination of the phosphonate group from an aminyl and an alkyl radical did not occur. On the basis of our findings, the use of an acylphosphonate as a carbonyl group radical acceptor was investigated. Radical cyclization of the acylphosphonate in the presence of hexamethylditin in benzene at 300 nm for 2 h gave a cyclopentanone or a cyclohexanone derivative in good yield without the formation of a direct reduction product. The reaction can be carried out in the presence of a catalytic amount of hexamethylditin (0.2 equiv.) under similar conditions. In addition, an alkyl phosphonothiolformate group can act as an alkylthiocarbonyl group equivalent radical acceptor, providing ready access to a thiolactone synthesis.Key words: radical, β elimination, acylation, cyclization, acylphosphonate.

Polarographic reduction of α-(4-ethylbenzoyl)-α,β-dibromopropionic acid on mercury dropping electrode

1979 ◽  
Vol 44 (4) ◽  
pp. 1318-1323
Author(s):  
Miloslava Počtová
Keyword(s):  
Electrochemical Reduction ◽  
Carbonyl Group ◽  
Polarographic Reduction ◽  
Polarographic Wave ◽  
Intermediate Products ◽  
Active Intermediate

A mechanism of the electrochemical reduction of β-(4-ethylbenzoyl)-α,β-dibromopropionic acid is suggested based on the results of classical polarography and polarography with Kalousek's switch and on the identification of the polarographically active intermediate products. The substance converts to β-4-ethylbenzoylacrylic acid on the electrochemical elimination of the bromine atoms, and the latter acid is reduced further to β-4-ethylbenzoylpropionic acid. The most negative polarographic wave corresponds to the reduction of the carbonyl group in the benzoyl part of the last acid.

119Sn, 13C and 1H NMR Spectra of Tris(1-butyl)stannyl D-Glucuronate

1997 ◽  
Vol 62 (8) ◽  
pp. 1169-1176 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
David Micák
Keyword(s):  
Chemical Shift ◽  
Carbonyl Group ◽  
1H Nmr ◽  
Equatorial Plane ◽  
Title Compound ◽  
Nmr Spectra ◽  
Hydroxyl Groups ◽  
Carboxylic Group ◽  
H Nmr ◽  
Oxygen Atoms

The 119Sn, 13C and 1H NMR spectra of tris(1-butyl)stannyl D-glucuronate have been measured in hexadeuteriodimethyl sulfoxide, tetradeuteriomethanol and deuteriochloroform. The chemical shift values have been assigned unambiguously with the help of H,H-COSY, TOCSY, H,C-COSY and 1H-13C HMQC-RELAY. From the analysis of parameters of 119Sn, 13C and 1H NMR spectra of the title compound and their comparison with the corresponding spectra of tris(1-butyl)stannyl acetate and other carboxylates it follows that in solutions of non-coordinating solvents (deuteriochloroform) the title compound is present in the form of more or less isolated individual molecules with pseudotetrahedral environment around the central tin atom and with monodentately bound carboxylic group. The interaction of tin atom with oxygen atoms of carbonyl group and hydroxyl groups of the saccharide residue - if they are present at all - are very weak. In solutions in coordinating solvents (hexadeuteriodimethyl sulfoxide or tetradeuteriomethanol), the title compound forms complexes with one molecule of the solvent. Particles of these complexes have a shape of trigonal bipyramid with the 1-butyl substituents in equatorial plane and the oxygen atoms of monodentate carboxylic group and coordinating solvent in axial positions.

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

scholarly journals Synthesis of a sucrose dimer with enone tether; a study on its functionalization

2014 ◽  
Vol 10 ◽  
pp. 1246-1254 ◽  
Author(s):  
Zbigniew Pakulski ◽  
Norbert Gajda ◽  
Magdalena Jawiczuk ◽  
Jadwiga Frelek ◽  
Piotr Cmoch ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Double Bond ◽  
Carbonyl Group ◽  
Osmium Tetroxide ◽  
Cd Spectroscopy ◽  
Allylic Alcohol ◽  
Circular Dichroïsm

The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD) spectroscopy using the in situ dimolybdenum methodology.

Synthesis of Polycycles and Oxacycles by Tandem Metathesis of endo–norbornene Derivatives

Synthesis ◽  
2021 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Sunil Pulletikurti ◽  
Ambareen Fatma ◽  
gopal dhangar ◽  
gonna somu Naidu
Keyword(s):  
Natural Products ◽  
Metal Complex ◽  
Carbonyl Group ◽  
Single Step ◽  
Time Dependent ◽  
Computational Studies ◽  
Nmr Studies ◽  
Tricyclic Compounds ◽  
One Step ◽  
Norbornene Derivatives

Here, we have demonstrated that the presence of a carbonyl group at C7 position is preventing the olefin metathesis of endo-norbornene derivatives due to the complexation of the metal alkylidene. Time-dependent NMR studies showed the presence of new proton signals in the metal alkylidene region, which indicate the formation of metal complex with the carbonyl group of the substrate. These observations were further proved by ESI-MS analysis. Whereas, computational studies provided that the catalyst was interacting with the C7 carbonyl group and aligned perpendicular to that of norbornene olefin. Later, these endo-keto norbornene derivatives were reduced to hydroxyl derivatives diastereoselectively. Ring-rearrangement metathesis (RRM) of these hydroxyl derivatives, produced the [6/5/6], and [5/6/5] carbo-tricyclic cores of the natural products in one step. Whereas the RRM of O-allyl derivatives, delivered the oxa-tricyclic compounds in a single step with excellent yields.

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