Abstract: The thermal decomposition of dimethyldodecylamine oxide at 125" in a sealed system produces 2-methyl-5-decylisoxazolidine (plus some olefin) and dimethyldodecylamine, rather than normal cycloelimination products. The anomalous products are suggested to result from a facile oxidation of N, N-dimethylhydroxylamine (DMHA) by tertiary amine oxide to N-methylnitrone, which is then trapped by olefin. The ...