191347-47-4Relevant academic research and scientific papers
Reactions of the 'stable' nitroxyl radical TEMPO with ketenes: Formation of a unique peroxidic source of aminyl radicals
Huang, Wen-Wei,Henry-Riyad, Huda,Tidwell, Thomas T.
, p. 3939 - 3943 (1999)
Calculations at the B3LYP level predict addition of the radical H2NO to the carbonyl carbon of CH2=C=O to be exothermic by 18.7 kcal/mol. Consistent with this prediction, the ketene Ph2C=C=O reacts at 25 ΔC with tetramethylpiperidinyloxy radical (TEMPO, TO) to yield an unstable species that reacts with oxygen to form the peroxide (OCPh2CO2T)2 (6, T = 2,2,6,6- tetramethylpiperidinyl), whose structure was confirmed by X-ray crystallography. Heating of 6 at 100 ΔC in toluene with TEMPO leads to Ph2C=O, tetramethylpiperidine, and PhCH2OT, indicating that 6 decomposes to form two 2,2,6,6-tetramethylpiperidinyl radicals 15. Kinetic studies of the thermal decomposition of 6 show a 100-fold rate acceleration relative to (PhMe2CO)2. Thermal reactions of TEMPO with the bisketene (Me3SiC=C=O)2 (23) at 90 °C and with the allenylketene 26 also lead to deoxygenation of TEMPO, forming radicals 15, together with 2,3-bis(trimethylsilyl)maleic anhydride (24) and the alkylidenelactone 27, respectively.
Metal-Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde-Derived Silyl Enol Ethers
Roy, Avijit,Oestreich, Martin
supporting information, p. 8273 - 8276 (2021/05/11)
Little-explored hydrosilylation of ketenes promoted by main-group catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enol ethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using dihydrosilanes. The related trityl-cation-initiated hydrosilylation involving self-regeneration of silylium ions is far less effective.
Unprecedented intramolecular [3 + 2] cycloadditions of azido-ketenimines and azido-carbodiimides. Synthesis of indolo[1,2-a]quinazolines and tetrazolo[5,1-b]quinazolines
Alajarin, Mateo,Bonillo, Baltasar,Ortin, Maria-Mar,Orenes, Raul-Angel,Vidal, Angel
experimental part, p. 6741 - 6749 (2011/11/05)
N-(2-Azidomethyl)phenyl ketenimines and N-(2-azidomethyl)phenyl-N′- alkyl(aryl) carbodiimides undergo, under mild thermal conditions, intramolecular [3 + 2] cycloaddition reactions between the azido group and either the CC or the distal CN double bonds of the ketenimine and carbodiimide functions respectively. The reaction products are indolo[1,2-a]quinazolines and/or indolo[2,1-b]quinazolines in the case of azido-ketenimines, and tetrazolo[5,1-b]quinazolines in the case of azido-carbodiimides. The formation of the two classes of indoloquinazolines implies the ulterior dinitrogen extrusion from the non-isolated, putative [3 + 2] cycloadducts between the azide and ketenimine functions, whereas in the case of azido-carbodiimides the initial cycloadducts, tetrazoloquinazolines, were cleanly isolated and further converted into 2-aminoquinazolines by thermally induced dinitrogen extrusion.
Ketene-forming eliminations from aryl bis(4′-chlorophenyl)acetates promoted by R2NH-R2NH2+ in aqueous MeCN. Change of mechanism
Pyun, Sang Yong,Lee, Dong Choon,Kim, Ju Chang,Cho, Bong Rae
, p. 2734 - 2738 (2007/10/03)
Elimination reactions of (4′-ClC6H4) 2CHCO2C6H3-2-X-4-NO2 promoted by R2NH-R2NH2+ in 70 mol% MeCN (aq.) have been studied kinetically. The reactions are second-order and exhibit Broensted β= 0.44-0.86 and |βlg| = 0.41-0.71. The Broensted β decreased with a poorer leaving group and |β lg| increased with a weaker base. The results are consistent with an E2 mechanism. When X = H, the reaction proceeded by the concurrent E2 and E1cb mechanism.
