No abstract

No abstract

No abstract

sulfuric acid, aqueous sodiuiri bicarbonate and water. Moisture was removed with sodium sulfate and the solution concentrated; dropwise addition of pentane yielded a fine powder (3.60 g., 99%) which was reprecipitated from diisopropyl ether by the addition of pentane and dried in DUCUO (0.1 mm.) a t 80" for 5 hr. Attempts to obtain this amorphous product in crystalline form failed. After chromatography on alumina it showed [ a ] "~ -21.3' in glacial acetic acid (c 4.85) and [ a ] " D -28.3" in ethanol (c 1.26). Anal. Calcd. for C~~H~Z O~( O Z C ? H~) , C O O H : neut. equiv., 117.1. Found: neut. equiv., 116.7.Cleavage of Steviolbioside Heptaacetate with Hydrogen Bromide in Glacial Acetic Acid.-A solution of 65 mg. of the heptaacetate in 1.5 ml. of glacial acetic acid was mixed with 0.13 ml. of a solution containing ca. 30% by weight of hydrogen bromide in glacial acetic acid. Polarimetric obscrvations showed a minimum rotation at 5 minutes followed by a slow dextrornutarotation to a positive value. After 36 hr. crystallization began and, after 50 hr., the crystals were removed. Recrystallized f r ( m dichloromethanectlier and dried in vaczio a t 90", the material (15 mg., 31%)

Methyl «-D-arabinofuranoside tribenzoate, prepared directly from D-arabinose, gives, on treatment with hydrogen bromide in glacial acetic acid, two new crystalline substances which are shown to be the anomeric halides, 2,3,5-tri-O-benzoyl-a-Darabinosyl bromide (V) and 2,3,5-tri-0-benzoyl-3-D-arabinosyl bromide (VI). Both bromides react very rapidly with methanol, the ß-anomer being observably slower than the -anomer.