(S)-2-((1S,2S)-2-Hydroxy-1,2-diphenyl-ethylcarbamoyl)-piperazine-1,4-dicarboxylic acid 1-benzyl ester 4-tert-butyl ester

(S)-2-((1S,2S)-2-Acetoxy-1,2-diphenyl-ethylcarbamoyl)-4-(4-tert-butyl-benzenesulfonyl)-piperazine-1-carboxylic acid benzyl ester