Lipase-catalyzed aza-Michael addition of amines to acrylates in supercritical carbon dioxide

BACKGROUNDAza-Michael addition, a powerful method for the synthesis of beta -amino carbonyl derivatives, has been extensively studied in organic chemistry. In this study, the efficient and chemoselective aza-Michael addition of amines to acrylates catalyzed by lipase in supercritical carbon dioxide (scCO(2)) was reported for the first time. RESULTSUnder the optimal conditions [amine (1mmol), acrylate (1mmol), novozym 435 (20mg), 40 degrees C, scCO(2) (25mL, 10 MPa)], the corresponding Michael adducts of amines to acrylates were exclusively obtained in high yields (60-93%) for a short reaction time (1 h). No aminolysis was observed when scCO(2) was used as reaction medium. Moreover, novozym 435 showed high reusability in scCO(2) for aza-Michael addition. CONCLUSIONThe excellent chemoselectivity and reusability of novozym 435 in scCO(2) indicate the method's great potential for practical application. (c) 2019 Society of Chemical Industry