Silica‐supported chitosan–osmium tetroxide complex catalyzed vicinal hydroxylation of olefins using hexacyanoferrate(III) ion as a cooxidant

Silica‐supported chitosan–osmium tetroxide complex was prepared by a very simple method. This complex (SiO 2 ‐CS‐OsO 4 ) has been found to be able to catalyze the dihydroxylation of styrene, α‐methyl‐styrene, 1‐heptene, 1‐octene and 1‐decene to get (R)‐(−)‐1‐phenyl‐1,2‐ethanediol, (R)‐(−)‐2‐phenyl‐1,2‐propanediol, (S)‐(−)‐1,2‐heptanediol, (S)‐(−)‐1,2‐octanediol and (R)‐(+)‐1,2‐decanediol in the presence of K 3 Fe(CN) 6 , K 2 CO 3 , t‐BuOH and water at room temperature and under atmospheric pressure. The optical yields amounted to 77.3%, 64.8%, 81.3%, 78.2% and 38.4% respectively, and the product yields were 65.5%, 70%, 89.4%, 51% and 49.6% respectively. The experimental results showed that the OsO 4 content in the SiO 2 ‐CS‐OsO 4 complex greatly affected the optical yield. This new polymer–Os complex was very easy to prepare and could be reused without any appreciable change in optical catalytic activity. Copyright © 2003 John Wiley & Sons, Ltd.