Scheme.

(a) H₂, Pd(OH)₂, EtOAc, 91%; (b) PhCH(OMe)₂, p-TsOH, CH₂Cl₂, 91%; (c) (COCl)₂, DMSO, Et₃N, CH₂Cl₂, −78 °C; (d) Ph₃P=CHCHO, benzene, reflux, 70% for 2 steps; (e) CH₂=CHMgBr, Et₂O, 0 °C; (f) Ac₂O, Et₃N, DMAP, CH₂Cl₂, 74% for 2 steps; (g) Pd(PPh)₄, NaN₃, THF–H₂O, 65 °C, 81%; (h) NaOH, MeOH–H₂O; (i) N-methylmorpholine, isobutyl chloroformate, serine methyl ester · HCl, THF, −30 to +23 °C, 80% 2 for steps; (j) Burgess salt, THF, reflux; (k) BrCCl₃, DBU, CH₂Cl₂, 0 to 23 °C, 62% for 2 steps