We found that the reaction of carboxylic acids 1 with 3 equivalents of a secondary amine in the presence of 33 mol. % of TaCl 5 in a solution of methylene chloride after refluxing for 5 hours gave amides 2 in 51-87 % yield (Table ). In the case of amination of heptanoic acid with dibenzylamine, the yield of carboxamide was 51% (Entry 4). Apparently, the decrease in the yield of the formed amide in the case of dibenzylamine is associated with steric hindrances arising from the interaction of heptanoyl chloride formed in situ with dibenzylamine. At present, we have failed to obtain betulinic acid amide in methylene chloride solution. It is possible that the inertness of betulinic acid is caused by the presence of hydroxyl group in the A ring that binds TaCl 5 reagent. The quantitative formation of oxoniobium and oxotitanium carboxylates as a result of the treatment of carboxylic acids with NbCl 5 and TiCl 4 is described in the literature . However, the generation of oxotitanium carboxylates requires the use of more amount of carboxylic acid than the formation of oxoniobium carboxylates. At the same time, the effect of steric factors on the yield of the formed amide (31%) was demonstrated by the example of the TiCl 4 -promoted amination reaction of pivalic acid using pyrrolidine in a tetrahydrofuran solution . The reaction of pivalic acid with diethylamine in a solution of methylene chloride in the presence of NbCl 5 gave the corresponding amide in 78% yield .