174740-42-2 AIDS-033475 AIDS033475 Betulinic acid NHPrCOOH deriv. Butanoic acid, 4-[[(3.beta.)-3-hydroxy-28-oxolup-20(29)-en-28-yl]amino]- N-[3.beta.-Hydroxylup-20(29)-en-28-oyl]-4-aminobutyric acid