Enantioselective enzymatic aminolysis of a racemic 2-isoxazolylacetate alkyl ester

The present invention relates to a process for the enantioselective enzymatic aminolysis of racemic 2-[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]acetate ((R/S)-I) by methyl Nα-Boc-L-α,β-diaminoproprionate.p-toluenesulfonic acid. More specifically, this invention pertains to a process for the enantioselective enzymatic aminolysis of racemic isobutyl 2-[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]-acetate by methyl Nα-Boc-L-α,β-diaminoproprionate.p-toluene sulfonic acid to produce (R)-methyl-3-[[[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]acetyl]amino]-N-(butoxycarbonyl)-L-alanine, an intermediate in the preparation of roxifiban, an isoxazoline-based platelet glycoprotein IIb/IIIa antagonist which has activity as an antithrombotic agent.