An unexpected product in attempted [4 + 2] cycloadditions of 2,2-diethyl-4,5-dimethyl-2H-imidazole.
2,2-Diethyl-4,5-dimethyl-2H-imidazole 1, formally a 1,4-diazadiene, does not produce [4 + 2] cycloadducts with various electronically-different dienophiles. In the presence of HO2CCF3, it tautomerizes to 2,2-diethyl-4-methyl-5-methylene-3-imidazoline 2 and forms a dimer I, the structure of which was detd. by x-ray crystallog.
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