The extremely low intrinsic reactivity of the P-(formylmethyl)triphenylphosphonium cation: an artefact due to strong covalent hydration of the carbonyl group

1999 ◽  
pp. 1287-1288 ◽  
Author(s):  
G. Moutiers ◽  
Y. X. Peng ◽  
A. Peignieux ◽  
M. J. Pouet ◽  
F. Terrier
Keyword(s):  
Carbonyl Group ◽  
Intrinsic Reactivity

Changing regioselectivity patterns in metal hydride reductions of unsymmetrically substituted cyclic anhydrides

1983 ◽  
Vol 61 (3) ◽  
pp. 439-441 ◽  
Author(s):  
Margaret M. Kayser ◽  
Judith Salvador ◽  
Peter Morand
Keyword(s):  
Carbonyl Group ◽  
Metal Hydride ◽  
Nucleophilic Additions ◽  
Substrate Molecule ◽  
Parent Molecule ◽  
Cyclic Anhydrides ◽  
Intrinsic Reactivity

A study of L- and K-selectride reductions of unsymmetrical cyclic anhydrides attached to six-membered rings and to bridged six-membered systems sheds a new light on the effect of the conformation of the substrate molecule on the regioselectivity of metal hydride reductions. Thus, in addition to intrinsic reactivity of the carbonyl group, the antiperiplanar effect, and steric congestion, the conformation of the parent molecule should be considered in predicting regioselectivity of nucleophilic additions to cyclic anhydrides.

Theoretical study of regioselectivity in nucleophilic addition to unsymmetrical cyclic anhydrides. Intrinsic reactivity and influence of the cation

1981 ◽  
Vol 59 (16) ◽  
pp. 2457-2462 ◽  
Author(s):  
Margaret M. Kayser ◽  
Odile Eisenstein
Keyword(s):  
Carbonyl Group ◽  
Nucleophilic Addition ◽  
Nucleophilic Attack ◽  
Dominant Factor ◽  
Molecular Orbital Calculations ◽  
Optimum Position ◽  
Cyclic Anhydrides ◽  
Intrinsic Reactivity ◽  
Reaction Media ◽  
Phthalic Anhydrides

Ab initio molecular orbital calculations have been carried out for the series of succinic, maleic, and phthalic anhydrides unsymmetrically substituted with CH3, CH3O, Cl, F, and CN. The size of the LUMO coefficient on the carbon atom of the carbonyl group provides a reliable guide to the relative reactivities of the two carbonyl functions. The predictions based on the intrinsic reactivities are in good agreement with the regioselectivities observed in metal hydride reductions of succinic anhydrides. In the series of maleic and phthalic anhydrides the above considerations are applicable only to methyl derivatives. The compounds substituted with lone pairs-bearing groups (OCH3, Cl, F) form stable chelates with the cations present in the reaction media. Since the chelated carbonyl group is strongly activated toward the nucleophilic addition, the "bridging" effect is the dominant factor controlling orientation of hydride addition. The optimum position for the nucleophilic attack in cyclic anhydrides was calculated. The results confirm the generality of the nonperpendicular, restricted path of nucleophilic attack on the carbonyl group in succinic anhydride.

Metal hydride reductions of unsymmetrically substituted cyclic anhydrides attached to strained ring systems

1982 ◽  
Vol 60 (10) ◽  
pp. 1199-1206 ◽  
Author(s):  
Margaret M. Kayser ◽  
Judith Salvador ◽  
Peter Morand ◽  
H. G. Krishnamurty
Keyword(s):  
Carbonyl Group ◽  
Metal Hydride ◽  
Theoretical Calculations ◽  
Ring Systems ◽  
Hydride Reduction ◽  
Cyclic Anhydrides ◽  
Intrinsic Reactivity

A dramatic reversal in regioselectivity is observed in the metal hydride reduction of unsymmetrical cyclic anhydrides such as 2,3, and 4 compared to cyclic anhydrides attached to bridged ring systems (e.g. 1). The synthesis of model cyclic anhydrides attached to strained rings is described and the ratios of isomeric lactones obtained upon reduction with metal hydride are reported. On the basis of theoretical calculations and, taking into account the intrinsic reactivity of the carbonyl group, the antiperiplanar effect, and steric congestion, an explanation is offered for the regioselectivity observed in the reduction of these compounds.

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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