Prepd by sodium amalgam reduction of an acid soln of the γ-lactone of l-gulonic acid: Fischer, Piloty, Ber. 24, 526 (1891). See also van Ekenstein, Blanksma, Rec. Trav. Chim. 27, 3 (1908); Levene, LaForge, J. Biol. Chem. 20, 430 (1915); Talen, Rec. Trav. Chim. 44, 891 (1925); Isbell, J. Am. Chem. Soc. 55, 2167 (1933). Synthesis from d-mannose: Evans, Parrish, Carbohydr. Res. 28, 359 (1973); from d-glucose: D. K. Minster, S. M. Hecht, J. Org. Chem. 43, 3987 (1978).