Scheme 1. Synthesis of HCT compounds 1–15 from simple isoquinolines. (a) Allyl chloroformate, MeMgBr, THF; (b) Pd(PPh₃)₄, morpholine; DDQ, CH₂Cl₂; (c) SeO₂, 1,4-dioxane, 60 °C; (d) appropriate thiosemicarbazide, HCl, EtOH, reflux or microwave 50 °C; (e) KNO₃, H₂SO₄; (f) Fe, HCl, MeOH, reflux; (g) Boc₂O, DMAP, TEA, THF; (h) Boc₂O, DMAP, TEA, THF; NaHCO₃, MeOH, reflux or K₂CO₃, MeOH, reflux; (i) NaH, THF; MeI. HCTs 1–3, 6–8, and 11–13 synthesized through route A; HCTs 5 and 10 synthesized through route B; HCTs 4, 9, 14, and 15 synthesized through route C. See Experimental section for full synthetic details.