Five New Alkaloids from the Leaves of Remijia peruviana

Abstract

Three new indolylquinuclidine-type alkaloids, remijinine (1), epiremijinine (2), and 5-acetyl-apocinchonamine (3), and two new cinchonine-derived alkaloids, N-acetyl-deoxycinchonicinol (4) and N-acetyl-cinchonicinol (5), as well as the known alkaloids quinamine, conquinamine, cinchonine, and quinidine were isolated from the leaves of Remijia peruviana. The structures of the new alkaloids were elucidated on the basis of spectroscopic analysis, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HMQC, and HMBC). The relative configuration at C-7 for remijinine (1) and, in consequence, for epiremijinine (2) was established by X-ray crystal structure analysis of the former.

Cinchona Alkaloids from Cinchona succirubra and Cinchona ledgeriana

“…The protons assignments of the quinuclidine moiety were established by HSQC, HMBC, and ROESY experiments, which were in agreement with a previous work [19]. The 1D (l " Tables 2 and 3) and 2D NMR data of compound 4 were similar to those of remijinine (10) [20]. A significant difference was a methoxyl group (δ H 3.78, δ C 56.3) substituted at C-10 of the benzene ring in 4, which presented the ABX proton spin system signals, and then was further supported by the HMBC cor- (J = 6.0 Hz), a doublet at δ H 6.76 (1H, d, J = 6.5 Hz) ascribed to an olefinic proton, and one characteristic terminal vinyl group.…”

“…Over the last thirty years, cinchona alkaloids have become increasingly popular in organic chemistry, being used as chiral catalysts, ligands, and NMR discriminating agents, among others [15][16][17][18]. The barks of several species of Cinchona and Remijia (Rubiaceae) trees have been proven to be good sources of cinchona alkaloids [1,3,4,14,[19][20][21][22]. Up to now, over 30 cinchona alkaloids have been characterized by structural and stereochemical investigations.…”

“…As a result, seven new cinchona alkaloids, including three quinoline alkaloids (1-3) and four indole alkaloids (4-7), together with 29 known compounds were isolated. The new alkaloids were elucidated by means of spectroscopic methods, while the known alkaloids were identified as cinchoninone (8) [26,34], cinchotoxine (9) [14], remijinine (10) [20], cinchonamine (11) [3], quinamine (12) [3], liriodenine (13) [35], lyscamine (14) [36], cinchophylline (15) [4], quinidinone (16) [37], quininone (17) [37], cinchonidinone (18) [38], quinine (19) [39], quinidine (20) [38], cinchonine (21) [5,19] [42], and alkaloid 376 (36) [43], by comparison with data in the literature. All compounds were evaluated for their cytotoxicity against five human cancer cell lines.…”

Highly Diastereo- and Enantioselective Synthesis of Quinuclidine Derivatives by an Iridium-Catalyzed Intramolecular Allylic Dearomatization Reaction

“…Quinuclidine, also named 1-azabicyclo[2.2.2]octane, exists in a number of naturally occurring compounds, biologically active agents, and privileged catalysts and ligands for asymmetric catalysis (Figure 1). [1][2][3][4][5][6] In particular, quinine, a kind of cinchona alkaloid, has been recognized as a medication for the treatment of malaria and babesiosis. 7,8 Quinuclidine derivatives are also widely utilized as homogeneous or heterogeneous catalysts in various asymmetric processes such as Morita-Baylis-Hillman reactions, 4 Sharpless dihydroxylation reactions, 5 and phase-transfer catalytic reactions.…”

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

“…Three new indolylquinuclidine-type alkaloids, remijinine (3), epiremijinine (4), and 5-acetylapocinchonamine (5) have been isolated from the leaves of Remijia peruviana. 10 The structures were established on the basis of spectral analysis. The relative configuration at C-7 of 3 was confirmed by X-ray crystal structure analysis of 3.…”