Reagents and conditions: (a)
(S)-4-ACPBPA 6 or (R)-4-ACPBPA 7 [for (R)-10d], NaHCO3, water/DME/THF (1:1:0.3), room temperature for
16 h, 81–89%; (b) TFA/DCM (1:1), room temperature for 1–2
h, 92–98%; (c) NMA N-succinimidyl ester, NaHCO3, water/DME/THF (1:1:0.3), room temperature for 16 h, 75–84%.