Scheme 1. Synthesis of the marine alkaloid granulatimide and isogranulatimide analogue compounds 44–48, 55–58, and 68–70. Reagents and conditions: (a) Br₂, DMF, 2 h; (b) TFA, CH₂Cl₂, r.t., 4 h; (c) SnCl₂, toluene, reflux, 24 h; (d) Pd, microwave 300 W, 190 °C, 15 min; (e) LiHMDS, THF, −15 °C then r.t., 12 h; (f) hν, CH₃CN, r.t., 5 h; (g) (COCl)₂, Et₂O, 25 °C, 3 h; (h) EtOH, Et₃N, 78 °C, 2 h; (i) i: t-BuOK, THF, r.t., 12 h; ii: HCl; (j) hν, CH₃CN, r.t., 5 h.