The synthesis and structure of novel chiral intermediate, 5-(l-menthyloxy)-3-bromo-2(5H)-furanone

In this paper, the synthetic method of the novel chiral intermediate, 5 - ( l - menthyloxy) - 3 - bromo - 2(5H) - furanone (5a) possessing special stru ctural properties and asymmetric reaction of 5a are investigated. The epime ric mixture of 5 - (l - menthyloxy) - 3 - bromo - 2(5H) - furranone (5a + 5 b) was prepared in 92% yield via bromination of epimeric mixture of 5 - (l - menthyloxy) - 2(5H) - furanone (3a + 3b) followed by elimination of hydro gen bromide. After 2 similar to 3 recrystallizations from petroleum ether, the optically pure 5a was obtained in 46% yield with d.e greater than or eq ual to 98%. Its structure and configuration were established on the basis o f the analytical and spectroscopic data, such as [alpha](D)(20), UV, IR, H- 1 NMR, C-13 NMR, MS and X - ray crystallography.