1: N-Fmoc-L-leucine With N-ethyl-N,N-diisopropylamine in dichloromethane T=20°C; 0.5 h; 2: With N-ethyl-N,N-diisopropylamine in methanol; dichloromethane 3: Fmoc-D-leucine-OH Further stages;

hydrogen; acetic acid; palladium on activated charcoal in ethanol

1: (hydrolysis) 2: H2, AcOH / Pd-C / aq. ethanol View Scheme

(i) ClCO2Et, Et3N, THF, (ii) /BRN= 1963940/, (iii) H2, Pd, MeOH; Multistep reaction;