Unusual reactivity of N-tert-butylimines under FVT conditions

Thermal reactions of N-tert-butyl-(E)-crotonaldimine (1a) and 1,4-di-(tert-butyl)-1,4-diazabuta-1,3-dien (glyoxal-bis-N-tert-butylimine) (1b) under FVT conditions have been studied. It has been found that at 800 °C compound 1a yielded pyrrole and crotononitrile, presumably via homolytic t-Bu-N bond cleavage and formation of the iminyl radical. In the reaction of 1b at 800 °C, 2-methylimidazole (4b) has been obtained unexpectedly as the major product. The mechanism of these reactions has been proposed. Furthermore, combined FVT and UV-photoelectron spectroscopy have been applied for direct generation and in situ characterization of compounds 1a and 1b under thermal activation conditions.