2‐Acetamido‐2‐deoxyaldonolactones from Sugar Formazans.

Abstract A new approach towards simple aldonic acid derivatives starting from the corresponding aldoses via the 2-acetamido-2-deoxy formazans resulted in the synthesis of 2-acetamido-2-deoxy- d -galactono-1,4-lactone (8), and its 6-deoxy (11) and 6-azido-6-deoxy (14) analogues on treatment with trifluoroacetic acid. The five-membered ring structure of the lactones and that of the intermediate lactone phenylhydrazone (7) was proved by 1H and 13C NMR studies, including deuterium-induced differential isotope shift (DIS) measurements. With sodium borohydride, lactones 8 and 11 were converted into 2-acetamido-2-deoxy- d -galactitol (15) and its 6-deoxy analogue (17), respectively.