1. 4-Methyl-5-(α-oxo-Β-bromo-e-ethoxycarbonylpentyl)imidazolinone-2 reacts with diethylamine with migration of the electrophilic reaction center to give 4-diethylaminomethyl-5-(α-oxo-e-ethoxycarbonylpentyl)imidazolinone-2. 2. Sulfur-containing nucleophilic reagents and potassium benzoate enter into a nucleophilic substitution reaction with 4-methyl-5-(α-oxo-Β-bromo-e-ethoxycarbonylpentyl)imidazolinone-2 without migration of the reaction center. 3. Direct conversion of 1,3-diacetyl-4-acetoxymethyl-5-(α-oxo-e-ethoxycarbonylpentyl)imidazolinone-2 to 4-methoxymethyl-5-(α-oxo-e-methoxycarbonylpentyl)imidazolinone-2, an intermediate product in the synthesis of the methyl ester of 3,4-dehydrobiotin, is realized by the reaction with a solution of sulfuric acid in methanol.