P 3073 (OTTO) 1-Propanephosphonic anhydride, 50 wt.% solution in 2-Methyltetrahydrofuran Cas 68957-94 - used as an acid-amine coupling reagent for the synthesis of 3-(trifluoromethyl)-1H-pyrazole-5-carboxamides which are potent activators of pyruvate kinase M2 (PKM2).