Table 1.

Influence of various enzymes on the esterification of erythro-1a with isopropenyl acetate (2a) in the ball mill.^a

Entry	Enzyme	1a:3a (%)b
1c	CALB	0:100
2	CALA	90:10
3	PS-IM	90:10
4	lipase A	100:0

^aReaction conditions: erythro-1a (50 mg, 0.15 mmol), enzyme (30 mg), 2a (0.6 mmol), 10 mL ZrO₂ milling jar, 6 ZrO₂ milling balls (5 mm in diameter), milling time 2 h, milling frequency 30 Hz. ^bDetermined by ¹H NMR spectroscopy. ^cMilling time 1 h. CALB (lipase B from Candida antarctica (expressed in Aspergillus niger) adsorbed on polymethacrylate beads, known also as Novozyme 345); CALA (lipase A from Candida antarctica, immobilized on Immobead 150, recombinant from Aspergillus oryzae); PS-IM (Amano lipase from Burkholderia cepacia immobilized on diatomaceous earth); Lipase A (Amano lipase A from Aspergillus niger).