Scheme 1. Synthesis of 3-Alkylpyridine Alkaloid Analogs 4a–d to 6a–d.

Reagents, conditions, and yields: (i) NaHSO₄, DHP, dimethyl sulfoxide (DMSO), hexane, 40 °C, 16 h, 74–89%; (ii) MsCl, Et₃N, CH₂Cl₂, rt, 10 h, 77–87%; (iii) 3-pyridinepropanol, NaOH/H₂O, Bu₄N⁺Br^–, Et₂O, rt, 72 h, 57–73%; (iv) MeOH, HCl, rt, 12 h, 71–100%; (v) (COCl)₂, Et₃N, DMSO, DCM, −60 °C, 25 min, 60–95%.