Triterpene saponins, methods of synthesis, and uses thereof

A method comprising the steps of:

• (a) providing a mixture of prosapogenins of formula IV-a:
• wherein:
• is a single or double bond;
• Y′ is hydrogen, halogen, alkyl, aryl, OR, ORy, OH, NR2, NHR, NH2, SR, or NROR;
• W is Me, —CHO,
• —CH2ORx, or —C(O)Ry;
• V is hydrogen or —ORx;
• Ry is —OH, or a carboxyl protecting group, wherein the carboxyl protecting group, when taken with its attached carbonyl group, is an ester, amide, or hydrazide;
• Rs1 is
• each occurrence of Rx′ is independently an optionally substituted group selected from 6-10-membered aryl, C1-6 aliphatic, or C1-6 heteroaliphatic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;
• or:
• two Rx′ are taken together to form a 5-7-membered heterocyclic ring having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;
• each occurrence of R is independently hydrogen, an optionally substituted group selected from acyl, arylalkyl, 6-10-membered aryl, C1-12 aliphatic, or C1-12 heteroaliphatic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;
• or:
• two R on the same nitrogen atom are taken with the nitrogen to form a 4-7-membered heterocyclic ring having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;
• and
• each occurrence of Rx is independently hydrogen or an oxygen protecting group selected from the group consisting of alkyl ethers, benzyl ethers, silyl ethers, acetals, ketals, esters, and carbonates;
• (b) treating said mixture of prosapogenins of formula IV-a under suitable conditions to form a mixture of prosapogenins of formula IV:
• wherein each of , Ry′ Y′, V, and W is as defined for compounds of formula IV-a, and each occurrence of Rx is independently hydrogen or an oxygen protecting group selected from the group consisting of alkyl ethers, benzyl ethers, silyl ethers, acetals, ketals, esters, and carbonates;
• Rs is
• with the proviso that at least one Rx group is not hydrogen;
• and
• (c) obtaining a prosapogenin of formula IV by suitable physical means.