1. Einwirkung von Aminen auf Dibromtriacetonamin
2. Bromination of 4 - oxo - 2,2,6,6 - tetramethylpiperidin - 1 -yloxy with phenyltrimethyl-ammonium perbromide in tetrahydrofuran (Organic Syntheses 53, 111 (1973)) gave a solid product presumed to be 3 - bromo - 4 - oxo - 2,2,6,6 - tetramethylpiperidin - 1 - yloxy. However, the yield of ~90% pure (tlc) material was low. After incubating this substance for 17hr/r.t. with benzylamine (2 mol equiv) in CH2Cl2, work up did not afford 3 - (N - benzyl)aminocarbonyl - 2,2,5,5 - tetramethylpyrrolidin - 1 - yloxy. However, treatment of the monobromonitroxide with NaOH aq in dioxan gave 3 - carboxy - 2,2,6,6 - tetramethylpyrrolidin - 1 - yloxy [m.p. 193–4° dec, 15% overall yield (3 steps) from 4 - oxo - 2,2,6,6 - tetramethylpiperidine; cf. 47% overall yield (5 steps) claimed in Ref. ,2].
3. A Short-cut to Spin-labelled Amides