A series of lupane C19-(1,2,3-triazolyl)-triterpenoids were obtained by “click” reaction of
3,28-diacetoxy-29-norlup- 20(30)-yne with different aromatic and sugar azides after screening of several
copper-based catalytic systems. DFT calculations were performed (B3LYP/6.311 level of theory)
and showed that the alkyne moiety is hindered by the triterpenoid skeleton, thus explaining its low reactivity
and the requirement of a very active catalytic system. Ultimately, it was found that the
dinuclear copper complex [Cu(µ-OH)(TMEDA)]2Cl2 is the most efficient catalyst. Moreover, for the
first time, a bis-(triazolyltriterpenoid)-derivative was obtained by the reaction of lupane C19-alkyne
with 1,4-bis(azidomethyl)benzene using the same catalyst.
Keywords: Triterpenoids, betulin, lupanes, 1, 2, 3-triazoletriterpenes, “click” reaction, C19-(1, 2, 3-triazolyl)-lupanes.
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