Synthesis of Betulonic and Betulinic Acids Derivatives with Sulfonamide Fragment Linked to the Triterpene Core by Amidoalkane Spaser

A series of potentially biologically active sulfonamides of betulonic and betulinic acids with a sulfonamide fragment containing residues of dibutylamine or N-heterocycles, which is linked to a triterpene core by an amidoethane or amidopropane spacer, was synthesized. Betulonic acid sulfonamides were obtained by chlorohydride conjugation of acid with 2-aminoethane and 3-aminopropanesulfonamides and used as precursor compounds for the transition to similar betulinic acid derivatives by selective reduction of the 3-keto group with the action of NaBH4 in EtOH. The structure of all synthesized triterpene sulfonamides was confirmed by 1D and 2D NMR spectroscopy and mass spectrometry.