Synthesis and Intramolecular Cyclization of a 2,3-seco-Oleanane Triterpenoid with an Ethylketone Fragment

Synthesis, Cyclization, and Cytotoxic Activity of 2,3-Secolupane Triterpenoids With an Ethylketone Fragment

“…Our group has reported 9 -12 that C(3) methyl substitution by Grignard reaction allows the modification of A-seco- and A-pentacyclic triterpenoids and the synthesis of novel biologically active derivatives. Thus, 2,3-seco-18αH-oleanane 3-methyl-3-ketone combining high virus-inhibitory activities against herpes simplex virus type 1 and HIV-1, 9 and 2,3-secolupane α-monobromomethyl ketone with a high antitumor activity 10,11 were synthesized.…”

“…Recently, we also described the synthesis of C(3)-ethyl substituted 18-αH-oleanane derivatives with weak cytotoxicity. 12 Therefore, to analyze comparatively reactivity and cytotoxic potential, we synthesized a series of lupane 3-ethyl substituted derivatives with a 2,3-fragmented and 5-membered ring A including products with a modified isopropylidene fragment. 3-(4,5-Dimethylthiazol-2-yl)-2,3-diphenyl-tetrazolium bromide (MTT) screening for cytotoxic activity, as well as a structure-activity relationship study of the semisynthetic products, were conducted.…”

Stereoselective Epoxidation of Triterpenic Allylic Alcohols and Cytotoxicity Evaluation of Synthesized Compounds

“…The transformation procedure for allobetulone ( 1 ) into 2-methyl-3-oxo-19β,28-epoxy-18α-olean-1-ene ( 2 ) was described by us earlier [ 21 ]. To expand the range of the substrates under study, we carried out the reduction of α,β-unsaturated ketone 2 using NaBH 4 , as well as its reductive alkylation using an appropriate Grignard reagent with the formation of a secondary 3 or tertiary 7 – 9 allylic alcohols (up to 75% yield), respectively.…”

“…Moreover, there have been synthesized new examples of antibacterial 1α,2α-epoxy-3β-hydroxy 18β-oleanolic acid ester derivatives that presumably regulate the metabolism, hemolysis, and β-lactamase gene expression [ 20 ]. The above findings prompted us to pay more attention to the transformation of the α-alkyl-substituted enone ( 2 ) previously synthesized from the triterpenoid allobetulone ( 1 ) in a few synthetic steps [ 21 ]. Introducing new oxygen-containing groups at the C1 and C2 positions of the enone ( 2 ) simultaneously can be attained through an epoxy group.…”