103525-89-9Relevant academic research and scientific papers
Synthesis of 2,6-Diazabicyclooct-7-ene-3,5-diones and 2(1H)-Pyridinones. - A Contribution to the Mechanism and to the Regiochemistry of 1,4-Dipolar Cycloaddition Reactions of New and Known 3,6-Dihydro-6-oxo-1-pyrimidinium-4-olates to Electron-rich and Electron-poor Alkynes
Gotthardt, Hans,Blum, Joachim,Schenk, Karl-Heinz
, p. 1315 - 1330 (2007/10/02)
The synthesis of some new representatives of the 3,6-dihydro-6-oxo-1-pyrimidinium-4-olates 3a-f is described.As masked 1,4-dipoles, the betaines 3a-d, g-i combine with bis(diethylamino)ethyne (4a), 1-(diethylamino)-1-propyne (4b), dimethyl acetylenedicarboxylate (4c), or methyl propiolate (4d) to produce the stable heterobicycles 5a-m, whereas the reactions of 3e,f with 4c or 3e with 4d proceed with elimination of phenyl isocyanate to give the 2(1H)-pyridinones 6g, i or 6h, respectively.At higher temperatures, the bicyclic primary adducts 5b-e, k, m also release phenyl isocyanate to form 2(1H)-pyridinone derivatives 6a-f in high yields.In the case of the cycloaddition of 3 to the unsymmetrical alkynes 4b, d the observed regioselectivities are in agreement with the results of MNDO calculations and the FMO and PMO theory.
