Nitrile oxides in medicinal chemistry. 4. Chemoenzymic synthesis of chiral heterocyclic derivatives

The two enantiomers of 3-bromo-5-(hydroxymethyl)-Δ 2 -isoxazoline (1) and 2-phenyl-5-(hydroxymethyl)-isoxazolidin-3-one (9) have been prepared in enantiomeric excess higher than 90% by hydrolysis of the corresponding butyrates under the catalysis of lipase PS, which was the most selective catalyst of the enzymes tested. The pairs of enantiomers of 1 and 9 were transformed into the chiral forms of the potent muscarinic ligands 3 and 5