Synthesis of nontrivial quinopimaric acid derivatives by oxidation with dimethyldioxirane

Oxidative lactonization of oleanane and ursane acids by treating with ozone

“…For example, the oxidation of methyl ursolate with ozone proceeds with generation of 12-oxo-11S,13R-oxetane fragment in the cycle С [21], whereas the oxidation of methyl oleanate leads to methyl 12-oxooleane [22]. Different courses of oxidation processes of triterpenoids belonging to the α-and β-amirine series with reagents like m-chloroperoxybenzoic acid and HCOOH-H 2 O 2 underlie their separation in the form of oxyderivatives, because in plants these metabolites often accompany each other [3,23,24].In continuation of our research on the oxidative transformations of vegetable terpenoids [25][26][27][28][29][30][31] we investigated in the present study the oxidation of С 12 =С 13 bond of the ring С in oleanane and ursane acids with ozone involving the free carboxy group (oxidative lactonization).Oxidative lactonization of oleanolic acid at the treatment with ozone was investigated before in various solvents (ethyl acetate, N,N-dimethylacetamide-MeOH, СН 2 Сl 2 -MeOH) with generation of three types of structures: 12α,13α-epoxides, 12α-hydroxy- …”

“…In continuation of our research on the oxidative transformations of vegetable terpenoids [25][26][27][28][29][30][31] we investigated in the present study the oxidation of С 12 =С 13 bond of the ring С in oleanane and ursane acids with ozone involving the free carboxy group (oxidative lactonization).…”

Synthesis and anticancer activity of quinopimaric and maleopimaric acids’ derivatives

“…The diterpenoids ability to induce apoptosis in different tumor cells is shown. 17,18 As a part of our program to investigate the plant terpenoids pharmacological potency, [6][7][8][19][20][21][22][23] especially to find cytotoxic agents among the levopimaric acid derivatives, we have realized the chemical transformations of levopimaric acid diene adducts with p-benzoquinone and maleic anhydride, resulting in more than twenty derivatives of quinopimaric and maleopimaric acids' with different double bonds, types of the E-ring and modification of the carbonyl-groups.…”

Oxidation of Methyl 2-Cyano-3,4-seco-4(23)-Ene-Ursolate by Ozone

“…We found earlier that oleanolic acid methyl ester was oxidized by ozone to methyl 12-oxoolean-28-oate [23] whereas oxidation of the analogous ursolic acid derivative gave 12-oxo-11S,13R-oxetane on ring C [24]. Limitations of methods for synthesizing such chiral non-racemic oxetanes were noted [25].Considering the aforementioned examples and continuing research on oxidative transformations of plant terpenoids [11,12,14,17,18,[26][27][28], we decided to determine the direction of the oxidation by ozone of 2-cyano-3,4-seco-4(23)-ene ursolic acid methyl ester (1) and to compare the results with those published for oxidation of the analogous oleanolic acid derivative [23].Oxidation of 1 with two unsaturated bonds in the C-4(23) (ring A) and C-12(13) (ring C) positions by ozone in CH 2 Cl 2 formed the three 2-cyano-3,4-seco-4-oxo derivatives 12-oxours-11S,13R-oxetane (2, 68%), 11-oxours-12-ene (3, 12%), and 12-hydroxy-4,11-dioxours-12-ene (4, 8%) (Scheme 1). Thus, oxidation of methyl 2-cyano-3,4-seco-4(23)-ene ursolate by ozone was non-selective, in contrast with the oxidation of the analogous oleanolic acid derivative, which enabled selective transformations of rings A and C to be carried out [23].…”

“…Considering the aforementioned examples and continuing research on oxidative transformations of plant terpenoids [11,12,14,17,18,[26][27][28], we decided to determine the direction of the oxidation by ozone of 2-cyano-3,4-seco-4(23)-ene ursolic acid methyl ester (1) and to compare the results with those published for oxidation of the analogous oleanolic acid derivative [23].…”