Scheme 1.

Synthesis of 6-6-6 (3), 6-7-6 (6), and 7-6-7 (9) DSTPs. a) 1. BzCl, NaHCO₃, CHCl₃ 2. HCl, MeOH 3. ClCH₂CH₂OH, KOH, EtOH 4. SOCl₂, CHCl₃ b) 1. NaOH, EtOH 2. aq. HCl 3. LiOH, H₂O c) 1,3-dibromopropane, NaHCO₃, EtOH d) 1. 1,2-dibromoethane 2. 10% aq. HBr 3. LiOH, H₂O e) 1. BzCl, AcOH, then NaOH 2. 1,2-dibromoethane, NaHCO₃ f) 1. 1,2-dibromoethane 2. 10% aq. HBr 3. LiOH, H₂O