Chemical transformations of betulonic aldehyde

Effective Three‐Step Construction of Betulonic Acid Hybrids with Heterocycle‐Containing Peptidomimetic Fragments

“…Starting betulonic acid (8) and its propargyl ester (9) were synthesized according to the literature procedures. [16,25] Aldehyde (15) was obtained by the procedure described earlier. [22] General procedure for the obtaining betulin 1…”

Liquid-Phase Oxidation of Betulin Over Supported Ag Nps Catalysts: Kinetic Regularities, Catalyst Deactivation and Reactivation

“…All these features of betulin impose certain restrictions on its oxidation in order to obtain its oxo-derivatives; in particular, there are substantial difficulties with controlling selectivity or in other words excess of oxidation. Currently the main method to produce these derivatives is betulin oxidation using strong and toxic oxidants containing chromium [26,27], manganese [28,29] or a mixture of TEMPO (2,2,6, 6-tetramethylpiperidin-1-oxyl), NaClO 2 and NaOCl [28,30]. These approaches are laborious and require complex purification steps, including column chromatography, multiple recrystallization and extraction using large volumes of solvent [31], making their use essentially unfeasible for large scale industrial applications.…”

The synthesis of α,β-unsaturated 18αH,19βH-ursane methyl ketones

“…The interest indicated by medicinal chemists in triterpenic carbon scaffolds is caused by attractive opportunities of improving physicochemical, pharmacokinetic, and pharmacodynamic properties of triterpenoids through their simple structural transformations, modifications of functional groups or the introduction of new reaction centers [7][8][9][10] . Considering that triterpenic oxo-derivatives are favorable objects for various chemical modifications, including the so-called aldol condensation forming new carbon-carbon bonds 11 , triterpenic α,β-unsaturated ketones were synthesized by a simple reaction of some aromatic and heterocyclic aldehydes as carbonyl component with triterpenic 3-ketones as a methylene component 7,[12][13][14][15][16] , while lupane 28-aldehyde was used as a carbonyl reactant in condensation with acetophenone 17 . The introduction of α,β-unsaturated oxo-fragment into triterpenic structures frequently enables to enhance synthetic 18,19 and biological 20,21 potentials of polycyclic triterpenoids.…”

“…The introduction of α,β-unsaturated oxo-fragment into triterpenic structures frequently enables to enhance synthetic 18,19 and biological 20,21 potentials of polycyclic triterpenoids. So, the transformations of the lupane α,β-unsaturated 3-ketones in reactions of reduction, oxidation, and cyclopropanation were investigated 15,16 . An additional structural modification of triterpenic skeleton proceeding with the creation of new reaction centers prospective for the realization of aldol condensation is regarded as a promising approach to expansion of the spectrum of triterpenic α,β-unsaturated ketones.…”