Synthesis of novel 5-(N-Boc-N-benzyl-2-aminoethyl)-7-oxo-4,7-dihydropyrazolo[1,5-a]pyrimidin-3-carboxamides and their inhibition of Cathepsins B and K

Abstract

Eight novel 5-(N-Boc-N-benzyl-2-aminoethyl)-7-oxo-4,7-dihydropyrazolo[1,5-a]pyrimidin-3-carboxamides were prepared in three steps from methyl 3-amino-1H-pyrazole-4-carboxylate and methyl 5-(benzyl(tert-butoxycarbonyl)amino)-3-oxopentanoate. The synthetic procedure comprises cyclocondensation of the above starting compounds, hydrolysis of the ester, and bis(pentafluorophenyl) carbonate (BPC)-mediated amidation. Title carboxamides were tested for inhibition of cathepsins K and B. The N-butylcarboxamide 5a exhibited appreciable inhibition of cathepsin K (IC₅₀ ~ 25 mM), while the strongest inhibition of cathepsin B was achieved with N-(2-picolyl)carboxamide 5c (IC₅₀ ~ 45 mM).