Scheme 2. Synthesis of psoralens with the cyclohexyl moiety at position 4′ with variation at position 3. Reagents and conditions: (a) 75% H2SO4, diethyl 2-acetylsuccinate (for 48) or diethyl 2-acetylglutarate (for 49), rt, 24 h; (b) MeOH, Br2, 0 °C to rt, 48 h; (c) 48 or 49, dioxane, K2CO3, KI, 100 °C, 24 h; (d) propan-2-ol, 1 M NaOH, 100 °C, 5–20 min; (e) 52 or 53, THF, N-hydroxysuccinimide, EDC, Et3N, 0 °C to rt, 24 h; (f) 52 or 53, THF, 2-(methylamino)acetonitrile, EDC, Et3N, 0 °C to rt, 24 h; (g) 52 or 53, THF, 2-aminoacetonitrile, EDC, Et3N, 0 °C to rt, 24 h.
