GC conditions: columns, β-Dex 225 (30 m × 0.25 mm × 0.25 μm) plus β-Dex 120 (30 m × 0.25 mm × 0.25 μm); oven temperature, 180°C; carrier gas He flow rate, 1.0 ml/min. (A) Chromatogram of lactone 1 standard with an approximate ratio of (3R,5S)/(3S,5R)/(3R,5R)/(3S,5S) = 1:1:3:3. (B) Chromatogram of actual sample from the chemoenzymatic process with an analysis result of >99.94% ee and 96.60% de using the indicated GC method. Peak 1, (3R,5R) or (3S,5S) stereoisomer; peak 2, (3R,5R) or (3S,5S) stereoisomer; peak 3, (3S,5R) stereoisomer; peak 4, (3R,5S) stereoisomer.