Ammonolysis of (5S)-N-(tert-butoxycarbonyl)-5-(methoxycarbonyl)-2-pyrroline with immobilized Candida antarctica lipase B (CAL B) in a packed bed reactor

Abstract

Abstract Conversion of (5S)-N-(tert-butoxycarbonyl)-5-(methoxycarbonyl)-2-pyrroline to its corresponding amide, an important intermediate in the synthesis of the dipeptidyl peptidase IV (DPP4) inhibitor Saxagliptin, was carried out by ammonolysis reaction catalyzed by immobilized Candida antarctica lipase B (Novozyme 435) in a packed bed reactor. The reaction proceeds smoothly at 50 °C in anhydrous tert-butanol containing 1.25 M ammonia and follows typical Michaelis-Menten kinetics with competitive product inhibition. The estimated kinetic parameters were Vmax 40 ± 4.4 mM h−1g−1, Km (216 ± 22 mM) and Ki 303 ± 31 mM. At substrate concentration of 30 mg/mL (132 mM) and flow rate of 0.1 mL/min, the product is obtained in >98% yield and 98.5% purity at steady state in a column (100 cm × 1.2 cm) packed with 40 g immobilized CAL B.