3,4-Disubstituted β-lactams 3-benzyloxy-4-(4-chlorophenyl)azetidin-2-one [(3S∗,4R∗)-(±)-1], 3-benzyloxy-4-phenylazetidin-2-one [(3S∗,4R∗)-(±)-2] and 4-(4-chlorophenyl)-3-phenoxyazetidin-2-one [(3S∗,4R∗)-(±)-3] were resolved through immobilized CAL-B-catalysed ring-cleavage reactions. Excellent enantioselectivities (E > 200) were obtained for (3S∗,4R∗)-(±)-1 and (3S∗,4R∗)-(±)-2 when the reactions were performed with added H2O as nucleophile in tert-butyl methyl ether at 70 °C, whereas only moderate E (12) was achieved for (3S∗,4R∗)-(±)-3 under the same conditions but in diisopropyl ether. The resulting ring-opened β-amino acids [(2R,3S)-4 (ee > 98%), (2R,3S)-5 (ee > 98%) and (2R,3S)-6 (ee = 50%)] and the unreacted β-lactams [(3S,4R)-1-3] (ee > 98%) could be easily separated.
- Candida antarctica lipase B
- Enzyme catalysis
- ß-amino acid
ASJC Scopus subject areas
- Process Chemistry and Technology