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.
Enantioselective Stetter Reactions Catalyzed by Bis(amino)cyclopropenylidenes: Important Role for Water as an Additive
Rezazadeh Khalkhali, Mehran,Wilde, Myron M. D.,Gravel, Michel
supporting information, p. 155 - 159 (2021/01/09)
The first highly enantioselective intermolecular Stetter reaction using simple enones is reported. A series of novel chiral BAC structures were designed and prepared. They were tested in the Stetter reaction with simple aldehydes and enones. The products were generated in excellent yields and enantioselectivities (up to 94% ee). Surprisingly, a substoichiometric amount of water was crucial to obtain high enantioselectivities. Chiral BACs were also shown to catalyze 1,6-conjugate addition reactions with paraquinone methides enantioselectively.
Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
, p. 2134 - 2141 (2021/09/29)
A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]