Acylation of 2,2,6,6-tetramethylpiperidine and 2,2,5,5-tetramethylpyrrolidine

Abstract

Treatment of 2,2,6,6-tetramethylpiperidine with carbonyl dichloride caused ring fission with loss of hydrogen chloride to give a mixture of 1,1,5-trimethylhex-4-enyl isocyanate and 1,1,5-trimethylhex-5-enyl isocyanate which on treatment with sodium carbonate gave N-(1,1,5-trimethylhex-4-enyl)-N′-(1,1,5-trimethylhex-5-enyl)urea. Ring fission also occurred on treatment with acetic anhydride or acetyl chloride, giving a mixture of N-(1,1,5-trimethylhex-4-enyl)acetamide and N-(1,1,5-trimethylhex-5-enyl)acetamide, although conditions could be modified to give 1-acetyl-2,2,6,6-tetramethylpiperidine. Treatment of 2,2,5,5-tetramethylpyrrolidine with carbonyl dichloride gave the 1-chlorocarbonyl derivative, which reacted normally with alcohols and amines.