Biocatalytic Acetylation of Primary Amines by Lipases under Orbital Shaking and Microwave Radiation

Abstract This paper addresses the effects of the concentration of lipases, temperature and solvent on the enzymatic acetylation of primary amines. (±)-Heptan-2-amine 1, (±)-4-phenylbutan-2-amine 2, (±)-1,2,3,4-tetrahydronaphthalen-1-amine 3 and (±)-2-methylcyclohexan-1-amine 4 were acetylated using 11 lipases to obtain amides under orbital shaking and microwave radiation. Under microwave radiation the same amines were acetylated only using the CALB. (±)-Heptan-2-amine 1 was subjected to kinetic resolution, under orbital shaking for 7 h employing CALB and ethyl acetate as acylating agent, and converted into (R)-N- (heptan-2-yl)acetamide 5 (c = 42%, 88% eep, hexane c = 52%, 81% eep, isopropyl ether; c = 40%, 65% eep, toluene). The reaction was fast (15 s) under microwave radiation in hexane and yielded acetamide 4 in high conversion (c = 91%), but without selectivity (5% eep).