Solid-phase parallel synthesis of trisubstituted dihydroimidazolyl dihydroquinoxalin-2(1H)-ones

An efficient approach for the solid-phase synthesis of dihydroimidazolyl dihydroquinoxalin-2(1H)-ones is described. Following reduction of a resin-bound amino acid amide, the primary amine of the resulting di-amine was selectively N-acylated with 4-fluoro-3-nitrobenzoic acid. Treatment with POCl3 led to formation of a dihydroimidazolyl derivative via dehydrative cyclization. Following displacement of the aryl fluoro group with an α-amino acid methyl ester, the dihydroimidazolyl moiety was alkylated with an alkyl halide. Reduction of aromatic nitro group with concomitant intramolecular cyclization using tin(II) chloride dihydrate led to formation of the dihydroimidazolyl dihydroquinoxalin-2(1H)-one. The compound was characterized by LC–MS, and 1H and 13C NMR spectroscopy.