Regioselective asymmetric aminohydroxylation of precursors to 2,3,6-trideoxy-3-aminohexoses

The catalytic asymmetric aminohydroxylation (AA) of 5-substituted-pent-2-en oates 8 and 17 was investigated as a route to 2,3,6-trideoxy-3-aminohexoses . The AA of ester 8, which bears a dimethyl acetal at C-5, favoured formati on of the a-amino regioisomer 11 with optimum regioselectivity being observ ed using (DHQ)(2)AQN as the chiral ligand and the chloramine salt of ethyl carbamate as the nitrogen source. Ester 17, which has a 4-methoxyphenoxy gr oup at C-5, undergoes highly regioselective AA affording the beta-amino reg ioisomer 19 in excellent enantiomeric excess, thereby establishing that int roduction of this aromatic group leads to a superior substrate for AA. (C) 2000 Elsevier Science Ltd. All rights reserved.