Solid-phase parallel synthesis of substituted dihydroimidazolylbutyl dihydroimidazol-3-ium salts

The solid-phase synthesis of pentasubstituted dihydroimidazolylbutyl dihydroimidazol-3-ium salts is described. Following reduction of Nα and Nε-diacylated dipeptide derived from resin-bound Nα-Fmoc-Nε-Boc-l-lysine, the resulting tetra-amine was selectively N-acylated at two positions with a carboxylic acid, with the N-acylation most likely occurring at the two internal amines. Treatment of this compound with POCl3 yielded the resin-bound pentasubstituted dihydroimidazolylbutyl dihydroimidazol-3-ium salt. The compounds were cleaved from the solid-support and extracted with 95% acetic acid in water.