495-71-6Relevant articles and documents
Synthesis and chemical transformations of partially hydrogenated [1,2,4]triazolo[5,1-b]quinazolines
Lipson,Desenko,Ignatenko,Shishkin,Shishkina
, p. 345 - 350 (2006)
The reaction of 5-methyl-7-phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a] pyrimidine with α,β-unsaturated carbonyl compounds in MeOH in the presence of MeONa affords partially hydrogenated aryl-substituted [1,2,4]triazolo[5,1-b]quinazolines. Hydrolysis, oxidati
Mechanistic investigations on the reaction between 1,2-dioxines and bulky stabilized phosphorus ylides: An efficient route to closely related cyclopropane stereoisomers
Avery, Thomas D.,Fallon, Gary,Greatrex, Ben W.,Pyke, Simon M.,Taylor, Dennis K.,Tiekink, Edward R. T.
, p. 7955 - 7966 (2001)
The bulky stabilized ylides (2a-d) react with a range of 1,2-dioxines (1a-d) to afford the diversely functionalized cyclopropanes 7 in excellent yield and diastereomeric excess. This is in direct contrast to the situation when nonbulky ester ylides are utilized which results in a completely different cyclopropyl series. Through a combination of isolation, spectroscopic, temperature, and deuterium and additive effects studies, the mechanism of cyclopropane formation from this second pathway can be proposed. Importantly, enolate quenching of the intermediate 1-2λ5-oxaphospholanes 4 prior to collapse results in an equilibrium mixture of intermediates 10 and 11 which have been fully characterized, and their formation is primarily a result of the steric bulk of the stabilized ester ylide. These intermediates (10/11) then collapse further and result in formation of the observed closely related cyclopropyl stereoisomers 7 and 8. Moreover, the addition of LiBr to these reactions allows for the control of which of the two possible cyclopropanation pathways will be dominant. Finally, optimal protocols that demonstrate the potential of this new cyclopropanation methodology for the ready construction of closely related cyclopropyl stereoisomers are presented.
Exploitation of ylide steric bulk to alter cyclopropanation outcome during the reaction of 1,2-dioxines and stabilised phosphorus ylides
Avery, Thomas D.,Greatrex, Ben W.,Taylor, Dennis K.,Tiekink, Edward R.T.
, p. 1319 - 1321 (2000)
The exploitation of ylide steric bulk to alter cyclopropanation outcome during the reaction of 1,2-dioxines and stabilised phosphorus ylides was discussed. It was found that sterically bulky ylides favoured the formation of a different distereomeric cyclopropyl series at ambient temperatures. The analysis showed that the use of sterically bulky ester ylides under concentrated conditions favoured the formation of the 'normal' trans isomer.
Synthesis of Unsymmetrical 1,4-Dicarbonyl Compounds by Photocatalytic Oxidative Radical Additions
Dong, Ya,Li, Ruining,Zhou, Junliang,Sun, Zhankui
, p. 6387 - 6390 (2021/08/23)
Herein we report a photocatalytic oxidative radical addition reaction for the synthesis of unsymmetrical 1,4-dicarbonyl compounds. This reaction utilizes a desulfurization process to generate electrophilic radicals, which add to α-halogenated alkenes and undergo further oxidation to deliver 1,4-dicarbonyl compounds. This mild and highly efficient method provides a valuable alternative to known strategies.
Electrochemical reactivity of S-phenacyl-O-ethyl-xanthates in hydroalcoholic (MeOH/H2O 4:1) and anhydrous acetonitrile media
López-López, Ernesto Emmanuel,López-Jiménez, Sergio J.,Barroso-Flores, Joaquín,Rodríguez-Cárdenas, Esdrey,Tapia-Tapia, Melina,López-Téllez, Gustavo,Miranda, Luis D.,Frontana-Uribe, Bernardo A.
, (2021/04/12)
The electrochemical behavior of a series of S-phenacyl-O-ethyl-xanthates (O-ethyl-dithiocarbonate acetophenone derivatives) in hydroalcoholic (MeOH/H2O 4:1) and anhydrous media (ACN/TBAPF6) using carbon electrodes was studied. Cyclic voltammetry showed in hydroalcoholic media only two cathodic waves, whereas in ACN one anodic and two cathodic waves were present. The first cathodic wave corresponded to the reduction of the phenylketone group, whereas the first anodic was attributed to the xanthate unit. Macroelectrolysis on graphite and vitreous carbon at anodic and cathodic potentials, let us to explore the synthetic potential of this electrochemical reactions. With some compounds in hydroalcoholic media and using carbon electrodes, polymeric material was deposited on the electrode impeding the reaction; this deposit was characterized by AFM and SEM-EDS. The electroreduction on Ti electrode overcome this problem and gave the corresponding acetophenones (>95%). On the other hand, in ACN, small quantities of the dimeric 1,4-dicarbonyl compounds X-PhCOCH2CH2COPh-X (7–15%), as well as the corresponding acetophenones (ca. 50%) were isolated. Oxidation macroelectrolysis showed a very complicated transformation without synthetic value. The reaction mechanism for the reduction and the homolytic dissociation into the phenacyl radical was supported by DFT calculations.
