Covalently Immobilized Lipases are Efficient Stereoselective Catalysts for the Kinetic Resolution of rac-(5-Phenylfuran-2-yl)-β-alanine Ethyl Ester Hydrochlorides

Lipase-catalyzed enzymatic resolution of several new, exotic and variously substituted rac-(5-phenylfuran-2-yl)-beta-alanine ethyl esters was investigated. Given the structural instability of unsubstituted rac-(5-phenylfuran-2-yl)-beta-alanine ethyl ester, we used the stable hydrochloride salt of this rac-heteroaryl-3-aminopropanoic acid ethyl ester as potential substrate to increase the scope of the reaction. Optimization experiments revealed an efficient procedure for both analytical-and preparative-scale (S)-selective hydrolysis of several racemic beta-amino ester hydrochlorides in NH4OAc buffer (20 mM, pH 5.8) at 30 degrees C. Enzymatic resolutions were performed with covalently bound lipase AK from Pseudomonas fluorescens and lipase PS from Burkholderia cepacia on Immobead T2-150 as catalyst. Seven out of eight new resolution products were successfully isolated and appropriately characterized.