Covalently Immobilized Lipases are Efficient Stereoselective Catalysts for the Kinetic Resolution of rac-(5-Phenylfuran-2-yl)-[beta]-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 °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.