Novel betulin derivatives as multidrug reversal agents targeting P-glycoprotein

Chemistry

All solvents were dried and purified prior to use according to standard procedures. When required, reactions were performed under inert atmosphere (Ar) in preflamed glassware. Anhydrous Na₂SO₄ was used for drying solutions, and the solvents were then routinely removed at ca. 40 °C under reduced pressure using a rotary vacuum evaporator. All reagents employed in the present work were commercially available and used without further purification. Among all the amines employed in the synthesis of the betulin carbamates, 6a-m and tert-butyl-4-(2-aminoethyl) piperazine-1-carboxylate,…