Chiral auxiliaries as docking/protecting groups: biohydroxylation of selected ketones with Beauveria bassiana ATCC 7159

The concept of chiral docking/protecting groups for biohydroxylation was extended from cyclopentanone to other ketones. Reaction of cyclohexanone, (R)-3-methylcyclohexanone, cycloheptanone, 5-methyl-2-hexanone and 4-methyl-2-pentanone with (R)-2-amino-1-propanol and subsequent in situ benzoylation afforded the corresponding N-benzoylated oxazolidine derivatives. All substrates were hydroxylated with the fungus Beauveria bassiana ATCC 7159, one of which was diastereoselectively hydroxylated with a d.e. of 99%. In this manner, access to the corresponding hydroxylated ketones was provided.