[Step 1] 3.2 g of a mixture of tert-butyl-5-amino-1H-benzo[d]imidazole-1-carboxylate and tert-butyl-6-amino-1H-benzo[d]imidazole-1-carboxylate and 671 mg of 1H-benzotriazole was dissolved in 90 mL of toluene followed by adding 6 mL of a toluene solution containing 0.9 mL of acetoaldehyde and stirring overnight at room temperature. Following completion of the reaction, 30 mL of heptane were added followed by stirring for 1 hour and concentrating under reduced pressure to obtain 5.2 g of a crude produce of tert-butyl-5-[1-(1H-benzo[d][1,2,3]triazol-1-yl)ethylamino]-1H-benzo[d]imidazole-1-carboxylate and tert-butyl-6-[1-(1H-benzo[d][1,2,3]triazol-1-yl)ethylamino]-1H-benzo[d]imidazole-1-carboxylate.
