Vitamin C and Isovitamin C Derived Chemistry. 3. Chiral Butenolides via Efficient 2,3-Didehydroxylations of L-Gulono-, D-Mannono-, and D-Ribono-1,4-lactones

Article abstract of DOI:10.1021/jo00238a028

Efficient, operationally simple procedures for preparing the chiral butenolides 3a, 4a, 13a,b, and 16a-d from the commercial L-ascorbic acid (L-threo-hex-2-enono-1,4-lactone) and D-isoascorbic acid (D-erythro-hex-2-eno-no-1,4-lactone) are described.The concept centers on the novel NaHSO3-induced regiospecific trans-β-bromo-acetoxy elimination of the readily accessible O-acetylated bromodeoxyaldono-1,4-lactones 10a,b to compounds 13a,b.These, on deacetylation and treatment of the resulting bromohydrins 16a,b with Ag2O, afford the enantiomerically pure epoxides 16c,d and thence, in boiling water, the corresponding diols 3a and 4a.In a similar manner NaHSO3 causes the D-ribono-1,4-lactone-derived bromo acetate mixture 17a,b to undergo elimination to the corresponding butenolides 18a,b, which, on subsequent hydrolysis and chromatographic purification, has given compound 1a in 48percent overall yield.