Scheme 7.
Reagents and conditions: (a) H2, Pd-C, EtOAc, 23 ºC, 16 h; (b) NaNO2, conc. HCl, CuCN, NaCN, H2O, 23 ºC, 3 h; (c) Boc2O, NiCl2·6H2O, NaBH4, MeOH, 23 ºC, 2 h; (d) MeI, KHMDS, THF, 23 ºC, 16 h; (e) LiOH·H2O, THF/H2O (9:1), 23 ºC, 16 h; (f) (R)-(+)-1-(1-naphthyl)ethylamine 18, EDCI, HOBT, DIPEA, CH2Cl2, 23 ºC, 16 h; (g) TFA, CH2Cl2, 23 ºC, 2 h.