A CNDO/2 study of reactivity of methylene group in 1-methyl-1,4-dihydronicotinamide

1982 ◽  
Vol 47 (6) ◽  
pp. 1621-1631 ◽  
Author(s):  
Jiří Krechl ◽  
Josef Kuthan
Keyword(s):  
Hydrogen Atom ◽  
Electronic Mechanism ◽  
Methylene Group ◽  
Reaction Profile

An attempt has been made to use the CNDO/2 method for prediction of the reaction profile and electronic mechanism of elimination of 4-hydrogen atom of 1-methyl-1,4-dihydronicotinamide (I).

EHT study of reactivity of methylene group in 1-methyl-1,4-dihydronicotinamide

1980 ◽  
Vol 45 (9) ◽  
pp. 2425-2432
Author(s):  
Jiří Krechl ◽  
Josef Kuthan
Keyword(s):  
Heterocyclic Ring ◽  
Covalent Bonds ◽  
Electronic Mechanism ◽  
Methylene Group ◽  
Plane Form ◽  
Reaction Profile

It has been demonstrated that the EHT method predicts an almost plane form of the heterocyclic ring in 1-methyl-1,4-dihydronicotinamide I (R = CH3) and also reflects satisfactorily character of the covalent bonds in the 4-methylene group. An attempt has been made of calculation of the reaction profile of elimination of the centre 4', and electronic mechanism of its splitting off is discussed.

Investigation of methylene group hydrogen atom reactivity in some azolidines

1967 ◽  
Vol 3 (2) ◽  
pp. 524-527
Author(s):  
S. N. Baranov ◽  
I. D. Komaritsa
Keyword(s):  
Hydrogen Atom ◽  
Methylene Group

Measurement of the Lamb shift in the hydrogen atom

1982 ◽  
Vol 138 (10) ◽  
pp. 347 ◽  
Author(s):  
Yurii L. Sokolov ◽  
V.P. Yakovlev
Keyword(s):  
Hydrogen Atom ◽  
Lamb Shift

Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism

2019 ◽  
Author(s):  
Shiori Date ◽  
Kensei Hamasaki ◽  
Karen Sunagawa ◽  
Hiroki Koyama ◽  
Chikayoshi Sebe ◽  
...  
Keyword(s):  
Natural Products ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Synthetic Method ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Hydride Hydrogen ◽  
Sulfur Heterocycles ◽  
One Step

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Synthesis of Spongidine A, D and Petrosaspongiolide L Methyl Ester Using Pyridine C-H Functionalization

2019 ◽  
Author(s):  
Florian Bartels ◽  
Manuela Weber ◽  
Mathias Christmann
Keyword(s):  
Natural Products ◽  
Methyl Ester ◽  
Hydrogen Atom ◽  
Phospholipase A2 ◽  
Late Stage ◽  
Hydrogen Atom Transfer ◽  
Ring System ◽  
Tetracyclic Core ◽  
Intramolecular Hydrogen ◽  
Phospholipase A2 Inhibitors

<div>An efficient strategy for the synthesis of the potent phospholipase A2 inhibitors spongidine A and D is presented. The tetracyclic core of the natural products was assembled via an intramolecular hydrogen atom transfer‐initiated Minisci reaction. A divergent late‐stage functionalization of the tetracyclic ring system was also used to achieve a concise synthesis of petrosaspongiolide L methyl ester.</div>

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