Table 2.

Biocatalytic reduction of cyclic ketones by enzyme variants IPR E238Y and MNMR Y244E.^[a]

Entry	Enzyme	Substrate	Product	Yield [%][b]	ee [%][b]
1 pH 6 2 pH 7	IPR E238Y IPR E238Y	3 a 3 a	8 a 8 a	<1 <1	nd nd
3 pH 6 4 pH 7	IPR E238Y IPR E238Y	1 a 1 a	2 b 2 b	38[c] 42[c]	45 (1S,2S,5R) 46 (1S,2S,5R)
5 pH 6 6 pH 7	IPR E238Y IPR E238Y	1 b 1 b	2 d 2 d	33[d] 47[d]	47 (1R,2S,5S) rac
7 pH 7	MNMR Y244E	5 c	6 c	3	nd

[a] Reactions (1 mL) were performed in buffer (50 mm KH₂PO₄ pH 6.0 for IPR; 50 mm Tris pH 7.0 for MNMR and IPR) containing monoterpenoid (1 a,b, 3 a,b, and 5 a–d; 5 mm), enzyme (5 μm or 10 μm for IPR and MNMR, respectively), NADP⁺ (10 μm), glucose (15 mm), GDH (10 U), and enzyme (2 μm). The reaction solutions were agitated at 25 °C for 24 h at 130 rpm. Product identification was performed by both comparing retention times with authentic standards and identification by GCMS on a DB‐WAX column (only GCMS identification for product 8 a). Figure S10 gives the GCMS spectra traces of the additional products and their respective substrates. [b] Product yield and enantiomeric excess were determined by GC analysis using DB‐WAX and Chirasil‐DEX‐CB columns, respectively. nd=not determined due to low product yield. [c] Other isomer formed (20 % yield) was 2 a. [d] Other isomer formed (2 % yield) was 2 c.