3.2. GC-MS of standard N-MC-TH~C-3-COOHME
GC-MS analysis of standard TH[3C-3-COOHs as
N-methoxycarbonyl methyl esters derivatives (NMC-
TH[3C-3-COOH-ME) provide chromatograms
as in Fig. 2. N-MC-MTCA-ME and N-MC-ETCAME
give rise to two peaks corresponding to (1R,3S)-
diastereoisomer (peak 1) and to (IS,3S)-diastereoisomer
(peak 2). To assign this configuration, the
diastereoisomeric peaks of standard were repetitively
separated by RP-HPLC, in which the configuration is