Highly exo-selective epoxidation and hydroxylation of triquinacene and its derivatives:: all-exo-hexahydroxytriquinane

Epoxidation of triquinacene 3 with dimethyldioxirane proceeded with a high degree of exo-face selectivity to give a quantitative yield of a 1:1.5 mixture of all-exo-4a and endo, exo, exo-triepoxytriquinane 4b. Subsequent lithium aluminum hydride reduction of the all-exo-triepoxide 4a gave all-exo-2,5,8-5a and all-exo-2,5,9-trihydroxytriquinane 5b, respectively. The straightforward S-fold dihydroxylation of triquinacene 3 led exclusively to the all-exo-hexahydroxytriquinane 8 in one step. X-ray crystal structure analyses confirmed the configuration of the triepoxide 4b and the hexaacetate 9 of the hexol 8.