Enantioselective synthesis and selective monofunctionalization of (4R,6R)-4,6- dihydroxy-2,8-dioxabicyclo[3.3.0]octane.

An efficient, enantioselective synthesis of a disubstituted bis-THF scaffold 5 is described, as well as an efficient differentiation of the 1,3-diol unit. [reaction: see text]

Short synthesis of enantiopure C2-symmetric 1,2:4,5-diepoxypentane and "pseudo"-C2-symmetric 3-azido-1,2:4,5-diepoxypentane from arabitol.

On the basis of our previously described selective protection of arabitol as its 1,2:4,5-bis-pentylidene acetal 5, we report a straightforward synthesis of the novel "pseudo"-C(2)-symmetric 3-azido-1,2:4,5-diepoxypentane building block 4 in 6 steps from arabitol. Using a similar synthetic route, an improved synthesis of the C(2)-symmetrical 1,2:4,5-bis-epoxypentane building block 1 is described, also in 6 steps from arabitol. Both enantiomers of 1 and 4 are accessible, and all reactions involved are easily amenable for large-scale synthesis.