Benzyl (S)-5-methyl-1,4-diazepane-1-carboxylate and benzyl (R)-5-methyl-1,4-diazepane-1-carboxylate were prepared from benzyl (S)-5-methyl-1,4-diazepane-1-carboxylate and benzyl (R)-5-methyl-1,4-diazepane-1-carboxylate, respectively, by separating the racemic mixtures of the mixtures by chiral high performance liquid chromatography (HPLC). The procedure was as follows: a 10 cm Chiralpak AD column was used with 15% 1:1 MeOH/EtOH and 85% hexane (containing 0.1% diethylamine) as the mobile phase at a flow rate of 200 mL/min. 1.14 g of the first-eluting enantiomer (>95% ee) was obtained and 1.15 g of the second-eluting enantiomer (>95% ee) was obtained under these conditions. will The first eluted enantiomer was named B-2 and used in the subsequent reaction.
