Scheme 3.

Preparation of compounds bearing a hydroxyl group within the linker^a

^a Reagents and Conditions: (a) allyl magnesium bromide, Et₂O, 0 °C to rt; (b) BH₃•THF, THF, 0 °C to rt, then NaOH, H₂O₂, H₂O, 0 °C to rt; (c) DMSO, (COCl)₂, NEt₃, DCM, −78 °C to rt; (d) 1-(2,3-dichlorophenyl)piperazine•HCl, NaBH(OAc)₃, DCE, rt; (e) TFA, DCM, rt; (f) N,N-dimethylcarbamyl chloride, DIPEA, DCM, rt; (g) 3-methoxyproponic acid, HCTU, DIPEA, DCM, rt.