Table 2.

Screening of acyl donors for the selective monoacetylation of dilignol erythro-1a.^a

Entry	R	Milling time (min)	1a:3a (%)b
1	isopropenyl (2a)	120	0:100
2	vinyl (2b)	120	6:94
3	phenyl (2c)	120	7:93
4	ethyl (2d)	120	70:30
5	isopropyl (2e)	120	66:34
6	allyl (2f)	120	63:37
7	tert-butyl (2g)	120	98:2
8c	H (2h)	90	100:0

^aReaction conditions: erythro-1a (50 mg, 0.15 mmol), CALB (30 mg of immobilized enzyme), acyl donor (0.60 mmol), 10 mL ZrO₂ milling jar, 6 ZrO₂ milling balls (5 mm in diameter). ^bDetermined by ¹H NMR spectroscopy. ^c10 equiv of 2h were used.