Asymmetric synthesis of l-carnitine from ( R)-3-chloro-1,2-propanediol

A practical chemical synthesis of l-carnitine ( 1) has been accomplished from ( R)-3-chloro-1,2-propanediol (( R)- 4), which is a main by-product originated from ( R, R)-Salen Co(III) catalyzed hydrolytic kinetic resolution (HKR) of (±)-epichlorohydrin. ( R)- 4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite (( R)- 5). The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds.