Vapour-assisted enzymatic hydrolysis of β-lactams in a solvent-free system

A new, solvent-free, vapour-assisted method, developed for the synthesis of carbocyclic cis β-amino acid enantiomers through the Candida antarctica lipase B-catalysed enantioselective (E >200) hydrolysis of β-lactams with 0.5 equiv of H2O at 70 °C, has been demonstrated to be applicable on a preparative scale to produce (±)-2 (the starting racemate for cispentacin), (±)-3 (the starting racemate for 4-tert-butylcispentacin, a new cispentacin analogue) and (±)-7 (the starting racemate for 1,4-ethylene-bridged cispentacin).