Synthèse et étude du réarrangement des diazoles-1,3: alkyl-1 alkylthio-2 (allylthio, arylthio, cycloalkylthio) imidazoles. Partie II. Réarrangement et réactions parasites

1979 ◽  
Vol 57 (7) ◽  
pp. 822-830 ◽  
Author(s):  
Jacky Kister ◽  
Georges Assef ◽  
Gilbert Mille ◽  
Jacques Metzger
Keyword(s):  
Structural Effect ◽  
Steric Effects ◽  
Steric Interactions ◽  
Ortho Effect ◽  
Rearrangement Reaction ◽  
Kinetics Of ◽  
Electronic And Steric Effects

The kinetics of the [Formula: see text] rearrangement reaction for a series of 1-alkyl-2-alkylthio (or allylthio, arylthio, cycloalkylthio) imidazoles has been studied at various temperatures. The rearrangement and hydrolysis results have been compared with those of 1-alkyl-2-methylthio-Δ-2-imidazolines and 1-alkyl-2-methylthio-Δ-2-tetrahydropyrimidines. Electronic and steric effects are discussed and a parallel between pKa and rearrangement is proposed. The limit of this parallel is either a structural effect such as direct (ortho effect) or indirect (cycle deformation) steric interactions or geometric modifications of the heterocycles studied (five- or six-membered cycles). All these results permitted the coherent choice of the amplification compound of a nonconventional photographic process.

Synthèse et étude du rearrangement des diazoles-1,3: alkyl-1 alkylthio-2 (allylthio, arylthio, cycloalkylthio) imidazoles. Partie I. Synthèse et études physicochimiques

1979 ◽  
Vol 57 (7) ◽  
pp. 813-821 ◽  
Author(s):  
Jacky Kister ◽  
Georges Assef ◽  
Gilbert Mille ◽  
Jacques Metzger
Keyword(s):  
Steric Effects ◽  
Hydrolysis Products ◽  
Physicochemical Studies ◽  
Kinetics Of ◽  
Electronic And Steric Effects

The synthesis and the [Formula: see text] rearrangement of thioethers in the N- and S-substituted imidazolic series have been studied (60 compounds). The physicochemical studies of the thioethers and mercapto compounds, catalysts of the rearrangement, and of the eventual hydrolysis products have been carried out and the kinetics of rearrangement have been examined at several temperatures. The rearrangement and hydrolysis results are compared with those of 1-alkyl-2-methylthio-Δ-2-imidazolines and 1-alkyl-2-methylthio-Δ-2-tetrahydropyrimidines and the electronic and steric effects are discussed. In this first part the synthetic aspect and physicochemicals results are presented.

Ortho Effect in the Bergman Cyclization:  Electronic and Steric Effects in Hydrogen Abstraction by 1-Substituted Naphthalene 5,8-Diradicals

2006 ◽  
Vol 110 (7) ◽  
pp. 2517-2526 ◽  
Author(s):  
Pickard ◽  
Rebecca L. Shepherd ◽  
Amber E. Gillis ◽  
Meghan E. Dunn ◽  
Steven Feldgus ◽  
...  
Keyword(s):  
Hydrogen Abstraction ◽  
Steric Effects ◽  
Bergman Cyclization ◽  
Ortho Effect ◽  
Electronic And Steric Effects

scholarly journals The ortho effect in directed C–H activation

2021 ◽  
Author(s):  
Balázs L. Tóth ◽  
Anna Monory ◽  
Orsolya Egyed ◽  
Attila Domján ◽  
Attila Bényei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Steric Effects ◽  
Ortho Effect ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The term and concept of Ortho Effect (OE) is introduced for the description of steric effects in transition metal catalyzed directed ortho C–H activation reactions to explain and predict reactivities of substrates.

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

Tetrahedron ◽  
2014 ◽  
Vol 70 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Xiaowei Sun ◽  
Chengzhe Gao ◽  
Fan Zhang ◽  
Zhuang Song ◽  
Lingyi Kong ◽  
...  
Keyword(s):  
Steric Effects ◽  
Schmidt Reaction ◽  
Benzyl Alcohols ◽  
Alkyl Azides ◽  
Electronic And Steric Effects

The Reactions of Substituted Germyl- and Silylhydrazines with BX3 and CY2 Acceptor Species

1972 ◽  
Vol 50 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. K. Peterson ◽  
K. I. Thé
Keyword(s):  
Molecular Weight ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Adduct Formation ◽  
Steric Effects ◽  
Reaction Products ◽  
Hydrazine Derivatives ◽  
Basic Catalysts ◽  
Series Of Experiments ◽  
Electronic And Steric Effects

Boron trimethyl reacts with each of the organometalloid-hydrazine derivatives Me2NN(R)GeMe3 (R = H, Me, SiMe3) except Me2NN(SiMe3)GeMe3, and with Me2NNHSiMe3, forming 1:1 adducts. With Me2NN(SiMe3)GeMe3 and BMe3, no adduct was formed even at low temperatures. On the basis of p.m.r. spectra, the metalloid-substituted nitrogen atom rather than the terminal nitrogen, is indicated as the basic center at which adduct formation occurs. With BF3, the Si—N and Ge—N bonds of the hydrazine derivatives were cleaved, again indicating attack at the central nitrogen atom. In a series of experiments involving CY2 (Y = O, S) and Me2NN(R)MMe3 (R = H, Me, SiMe3; M = Si, Ge), reaction occurred readily for R = H, but less readily for R = Me and for the compound Me2NN(GeMe3)2, while no reaction was observed for the compounds Me2NN(SiMe3)2 and Me2NN(SiMe3)GeMe3, even when heat or basic catalysts were employed. Reaction products, carbamate and thiocarbamate derivatives, Me2NN(R)C(Y)YMMe3, were characterized on the basis molecular weight, i.r., p.m.r., and mass spectroscopy, and m.p. data. Ease of formation is discussed in terms of electronic and steric effects.

The structural effect on the kinetics of acid leaching refining of Fe-Si alloys

1994 ◽  
Vol 38 (4) ◽  
pp. 342-347 ◽  
Author(s):  
F. Margarido ◽  
M.H. Bastos ◽  
M.O. Figueiredo ◽  
J.P. Martins
Keyword(s):  
Acid Leaching ◽  
Structural Effect ◽  
Kinetics Of

Highly Stereo- and Regioselective Allylations Catalyzed by Mo−Pyridylamide Complexes:  Electronic and Steric Effects of the Ligand

2000 ◽  
Vol 65 (18) ◽  
pp. 5868-5870 ◽  
Author(s):  
Oscar Belda ◽  
Nils-Fredrik Kaiser ◽  
Ulf Bremberg ◽  
Mats Larhed ◽  
Anders Hallberg ◽  
...  
Keyword(s):  
Steric Effects ◽  
Electronic And Steric Effects
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