Dedicated to Professor Dieter Enders on the occasion of his 70th birthday
Abstract
Treatment of α-hydroxy-substituted methoxyallene derivatives with meta -chloroperbenzoic acid provided acyloxy-substituted 1,2-diketones in moderate yields.
A mechanism for the formation of these unexpected products is proposed. The configuration
of the enantiopure compound (S )-1-(3-methylquinoxalin-2-yl)-1-(4-nitrobenzoyloxy)propan-2-yl 3-chlorobenzoate –
determined by X-ray crystal structure analysis – indicates the intermediacy of a carbenium
ion during formation of the 1,2-diketones. The functionalized 1,2-diketones are valuable
starting materials for a variety of products as demonstrated by the synthesis of quinoxalines,
an imidazole derivative, and electron-deficient alkenes.
Key words allenes - alkoxyallenes - quinoxalines - oxidation - peroxides - ring closure - rearrangement
- 1,2-diketones