145355-48-2Relevant articles and documents
Aryliminopropadienone-C-Amidoketenimine-Amidinoketene-2-Aminoquinolone Cascades and the Ynamine-Isocyanate Reaction
Wentrup, Curt,Rao, V. V. Ramana,Frank, Wilhelm,Fulloon, Belinda E.,Moloney, Daniel W. J.,Mosandl, Thomas
, p. 3608 - 3619 (2007/10/03)
Imidoylketenes 11 and oxoketenimines 12 are generated by flash vacuum thermolysis of Meldrum's acid derivatives 9, pyrrolediones 17 and 18, and triazole 19 and are observed by IR spectroscopy. Ketenimine-3-carboxylic acid esters 12a are isolable at room temperature. Ketenes 11 and ketenimines 12 undergo rapid interconversion in the gas phase, and the ketenes cyclize to 4-quinolones 13. When using an amine leaving group in Meldrum's acid derivatives 9c, the major reaction products are aryliminopropadienones, ArN=C=C=C=O (15). The latter react with 1 equiv of nucleophile to produce ketenimines 12 and with 2 equiv to afford malonic acid imide derivatives 16. N-Arylketenimine-C-carboxamides 12c cyclize to quinolones 13c via the transient amidinoketenes 11c at temperatures of 25-40 °C. This implies rapid interconversion of ketenes and ketenimines by a 1,3-shift of the dimethylamino group, even at room temperature. This interconversion explains previously poorly understood outcomes of the ynamine-isocyanate reaction. The solvent dependence of the tautomerism of 4-quinolones/4-quinolinols is discussed. Rotational barriers of NMe2 groups in amidoketenimines 12c and malonioc amides and amidines 16 (24) are reported.
Iminopropadienones, RN=C=C=C=O : Theory and Experiment
Mosandl, Thomas,Stadtmueller, Stefan,Wong, Ming Wah,Wentrup, Curt
, p. 1080 - 1086 (2007/10/02)
Ab initio molecular orbital calculations at the MP2/6-31G* level have been used to examine the structures and infrared spectra of a new class of compounds, the iminopropadienones, RN=C=C=C=O (R=H, CH3 and Ph).The agreement between calculated and experimental IR spectra of PhNCCCO,Ph(15)NCCCO, and PhNCC(13)CO is excellent.Inclusion of electron correlation is found to be important for the correct prediction of the relative intensities of the cumulenic stretching vibrations.As three iminopropadienones are predicted to have a slightly bent NCCCO backbone (CCC ca. 176 deg).As with carbon suboxide, these cumulenes are calculated to have an extremely flat CCC bending potential.The parent compound, HNCCCO (4a) is calculated to be thermodynamically stable toward dissociations into (i) HNCC + CO, (ii) HNC + CCO, (iii) HN + CCCO, and (iv) H. + NCCCO..Rearragement of 4a to the more stable cyanoketone isomer requires a sizeable barrier of 402 kJ mol-1 .The calculated stability of 4a is consistent with its experimental observation in neutralization-reionization mass spectrum.The adiabatic ionization energy and heat of formation of HNCCCO are predicted to be 9.51 eV and 175 kJ mol-1, respectively.
