Nonetheless, as the pH was increased from 7.0 to 7.5, the isomer in the isolated product decreased (Entries 2 and 3). Similarly, at pH 8.0-8.10 (Entries 4 and 5), only trace amounts of the isomer were observed. At pH 8.2 and 8.5 (Entries 6 and 7), there was virtually no isomer observed in the spectrum (Figure ), affording the target product in 99.3% purity by GC assay.