Enzymatic resolution of (±)-2-( Nβ- t-butoxycarbonyl -Nα-methylhydrazino)cycloalkanols

Abstract

Racemates of cis- and trans-2-( N β- t-butoxycarbonyl- N α-methylhydrazino)cyclopentanols and -cyclohexanols 1– 4 were resolved through lipase PS- or Novozym 435-catalysed asymmetric acylation of the secondary OH group at the ( R) -stereogenic centre. High enantioselectivity ( E >200) was observed when vinyl acetate or vinyl butyrate was used in diisopropyl ether, resulting in the enantiopure hydrazino esters 1a– 4a and hydrazino alcohols 1b– 4b. Methanolysis of the esters 1a– 4a afforded the corresponding 2-hydrazinocycloalkanols 1c– 4c (ee usually >95%).