A. Maquestiau, A. Tommasetti, C. Pedregal-Freire
Feb 1, 1986
Citations
0
Influential Citations
9
Citations
Journal
Journal of Organic Chemistry
Abstract
4-Carbonyl-4H-imidazole (10) and 2-carbonyl-2H-imidazole (11) are formed by flash vacuum pyrolysis of methyl 4- and 2-imidazolecarboxylates, respectively. 10 and 11 dimerize to diketopiperazines 14 and 16, respectively. The same products are also obtained from 4- and 2-(anilinocarbonyl)imidazoles, respectively. Methyl imidazole-1-carboxylate (4) on pyrolysis gives a ca. 1:1 mixture of the same ketenes 10 and 11, which dimerizes to a 1:2:1 ratio of diketopiperazines 14–16. In contrast, ethyl imidazole-1-carboxylate gave CO, ethylene, and imidazole as the major products. The pyrolysis reactions were monitored by low-temperature infrared and high-temperature mass spectrometry.