Decoration of A-Ring of a Lupane-Type Triterpenoid with Different Oxygen and Nitrogen Heterocycles


Betulinic acid (BA) was used as starting building block to create a library of novel BA-derived compounds containing O- and N-heterocycles. Firstly, BA was converted into methyl betulonate (BoOMe), which was used as intermediate in the developed methodologies. 1,2-Oxazine-fused BoOMe compounds were obtained in 12-25% global yields through a Michael addition of nitromethane to methyl (E)-2-benzylidenebetulonate derivatives, followed by nitro group reduction and intramolecular cyclization. Remarkably, the triterpene acts as a diastereoselective inducer in the conjugate addition of nitromethane, originating only one diastereomer out of four possible ones. Furthermore, other oxygen and nitrogen-containing heterocycles were installed at the A-ring of BoOMe, affording 2-amino-3-cyano-4H-pyran-fused BoOMe, diarylpyridine-fused BoOMe and 1,2,3-triazole-BoOMe compounds, using simple and straightforward synthetic methodologies. Finally, BA was revealed to be a versatile starting material, allowing the creation of a molecular diversification of compounds containing a triterpenic scaffold and O- and N-heterocycles.




Biochemistry & Molecular Biology; Chemistry


Sousa, JLC; Albuquerque, HMT; Silvestre, AJD; Silva, AMS

nossos autores


This work was financed by Portugal 2020 through FEDER in the frame of POCI and in the scope of the projects: MultiBiorefinery (POCI-01-0145-FEDER-016403), CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020) and LAQV-REQUIMTE (UIDB/50006/2020), co-financed by FCT/MCTES. Joana Sousa and Helio Albuquerque acknowledge the EpigenGlicON project (POCI-01-0145-FEDER-029767) for their researcher contracts.

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