. 2013 Nov 18;9:2544–2555. doi: 10.3762/bjoc.9.289

Table 4.

Optimization of conditions for Ru–lipase-catalysed DKR of 21.

entry	conditions^a	26	(2S)-21^b,c	13^c

1^d	Novozym 435, iPPA (1.0 equiv), toluene, 20 °C, 24 h	49%	44%	n. d.
2^d	C (2 mol %), Novozym 435, iPPA (10.0 equiv), toluene, 70 °C, 72 h	17%	n. d.	65%
3^d	C (1 mol %), Novozym 435, iPPA (10.0 equiv), Na₂CO₃ (1.0 equiv), toluene, 70 °C, 24 h	30%	n. d.	30%
4^d	D (2 mol %), Novozym 435, iPPA (1.5 equiv), Na₂CO₃ (1.0 equiv); t-BuOK (5 mol %), toluene, 20 °C, 7 d	50%	38%	n. d.
5^d	D (2 mol %); Novozym 435, iPPA (1.5 equiv), t-BuOK (5 mol %), toluene, 20 °C, 7 d	50%	n. i.	n. d.
6^d	D (2 mol %), Novozym 435, iPPA (3.0 equiv), Na₂CO₃ (1.0 equiv), t-BuOK (3 mol %), toluene, 30 °C, 7 d	67%	31%	n. d.
7^e	D (5 mol %), Novozym 435, iPPA (1.5 equiv), Na₂CO₃ (1.0 equiv), t-BuOK (6 mol %), toluene, 30 °C, 5 d	76%	20%	n. d.
8^f	D (5 mol %), Novozym 435, iPPA (3.0 equiv), Na₂CO₃ (1.0 equiv), t-BuOK (6 mol %), toluene, 30 °C, 14 d	80%	n. i.	n. d.

^aiPPA: isopropenyl acetate; ^bn. d.: not determined; ^cn. i.: not isolated; ^ddr’s of 26 and (2S)-21 >19:1; ^edr of 26 = 6:1; ^fdr of 26 = 3:1.