Synthesis of .alpha.-cyano carbonyl compounds by flash vacuum thermolysis of (alkylamino)methylene derivatives of Meldrum's acid. Evidence for facile 1,3-shifts of alkylamino and alkylthio groups in imidoylketene intermediates
摘要:
The syntheses and flash vacuum thermolyses of 5-[(alkylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones (Meldrum's acid derivatives) 13a-i are described. Thermolysis of 13a as well as of ethyl 3-(tert-butylamino)acrylate (22) gives a tautomeric mixture of cyanoacetaldehyde (14) and 3-hydroxypropenenitrile (15). Thermolysis of 13b gives iminoacrolein 26 and not cyanoacetone (29). Thermolysis of 13c,d gives S-methyl cyanothioacetate (30), and 13f-h give cyanoacetamides 31 in high yields. 2-Cyanopent-4-enoic acid derivatives 32 are obtained from Meldrum's acids 13e,i. The results are discussed in terms of facile 1,3-shifts of methylthio and alkylamino groups in imidoylketenes, interconverting imidoylketenes and acylketene imines.
作者:Felix Krischer、Varre S. V. S. N. Swamy、Kai‐Stephan Feichtner、Robert J. Ward、Viktoria H. Gessner
DOI:10.1002/anie.202403766
日期:2024.5.13
The synthesis and gram-scale isolation of the elusive cyanoketenyl anion [NC3O]− is reported. Despite its cumulene-like structure, it exhibits a bent geometry in the solid state, which is also confirmed by computational studies. The cyanoketenyl anion readily reacts with a series of small molecules such as CO2, H2O or NH3 to form more complex organic compounds, including industrially valuable compounds