| Popis: |
A new synthesis of l - threo -hex-2-enaro-1,4-lactone ( 4 ) (“saccharoascorbic acid”) is presented, whose unique feature involves oxidation of the side chain of ascorbic acid. Ascorbate 2-sulfate ( 1 ) was selectively oxidized in water at pH 8–8.5 with platinum-on-carbon catalyst to yield the 2-sulfate ( 3 ) of 4 . Hydrolysis of 3 in 15% trifluoroacetic acid for 90 min at 70° yielded 4 . The procedure affords a useful preparation of 4 , and demonstrates the excellence of sulfation for protection of the enediol of ascorbic acid during synthetic manipulations of the side chain. The sulfated ring is stable to oxidizing agents and to base, yet sulfate is readily removed by acid hydrolysis. The properties of a new compound ( 3 ) of biological significance, and those of the previously uncharacterized 4 , are reported. |
