Synthesis, structure and in vitro biological evaluation of new lupane and dammarane triterpenoids fused with pyrazine heterocycle

Derivatives of natural lupenone, dipterocarpol, alnincanone and semisynthetic dipterocarpol lactone fused with pyrazine heterocycle along C²–C³ positions were obtained by the Willgerodt–Kindler reaction, X-ray analysis having been used for the structure identification. Anti-influenza and anti-proliferative activities of the compounds obtained were estimated.