Solid-Phase Synthesis of Benzofused Tricycles

Significance

Benzofused tricycle libraries of ­pyrimido[1,2-a]benzimidazol-2(1H)-ones 4 and 1,2-dihydro-3H-[1,4]diazepinno[1,2-a]benzimidazol-3-ones 8 were prepared via solid-phase synthesis. Thus, the tricycles 4 were prepared by ­reaction of resin-bound diamines 1 and isothio­cyanates 2 in the presence of DIC, followed by treatment with K₂CO₃ and subsequent cleavage with H₂O₂. The tricycles 8 were prepared from 1 and Fmoc-α-amino acids 5 via peptide-bond formation, the successive cyclization with AcOH and piperidine, and β-elimination of the seleno resin.