Cyclopropanation and epoxidation of 2-ylidene derivatives of lupane series

Crotone condensation of allobetulone with fluorine-containing benzaldehydes afforded new α,β-unsaturated ketones of lupane series. Their transformations in reactions of reduction, oxidation, and cyclopropanation were investigated. The structures of the transformation products were established by X-ray diffraction analysis. The ability of obtained compounds to induce a cholesteric mesophase in nematic solvent 4'-pentyl-1,1'-biphenyl-4-carbonitrile was evaluated.