Scheme 2.

Reagents and conditions for preparation of compounds 11, 12a–f and 15a, b: (a) n-PrNH₂ (1 eq), CH₂Cl₂, rt (b) 2-bromoacetyl bromide (1 eq) and pyridine (2 eq), CH₂Cl₂, 0 °C to rt (two steps) (c) aldehyde (1 eq), NaOAc (2 eq), AcOH, 85 °C (d) BBr₃ (8 eq), CH₂Cl₂, −78 °C to rt (e) For 12a–c. amine (3 eq) or alcohol (5 eq), HOAt (1.5 eq), EDC (1.5 eq), DIPEA (2.5 eq), CH₂Cl₂, rt (f) For 12d–f. alcohol, alkyl chloride or alkyl tosylate (1.1–1.5 eq) K₂CO₃ (1.5 eq), NaI (0.1 eq), DMF, 70 °C (g) NEt₃ (3 eq), EDC (1.1 eq), HOAt (1.1 eq), alcohol (1.5 eq) rt (h) BBr₃ (5 eq), CH₂Cl₂, −78 °C to rt. eq: equivalent; rt: room temperature; HOAt: 1-Hydroxy-7-azabenzotriazole; EDC: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide; DIPEA: N,N-Diisopropylethylamine; DMF: dimethyl formamide.