Preparation and Conformational Study of B-Ring Substituted Lupane Derivatives
01 Jan 2006-Collection of Czechoslovak Chemical Communications (Institute of Organic Chemistry and Biochemistry AS CR, v.v.i.)-Vol. 71, Iss: 8, pp 1131-1160
TL;DR: In this paper, the conformation of lupane-type triterpenoids with a substituent on ring B was elucidated on the bases of 1 H and 13 C NMR spectra and molecular modelling.
Abstract: New lupane-type triterpenoids with 5(6) double bond were prepared using the method of partial demethylation on carbon C-4. Hydroboration of the double bond led to 6α-hydroxy derivative. By the oxidation and following reduction of 6α-hydroxy derivative the 6-oxo and 6β-hydroxy derivatives were prepared. A new method for selective oxidation of secondary hydroxy group in the presence of primary hydroxy group was performed. The conformation of ring A of new lupane-type 3-oxo derivatives with a substituent on ring B was elucidated on the bases of 1 H and 13 C NMR spectra and molecular modelling.
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TL;DR: The main methods for the synthesis of derivatives of A-seco pentacyclic triterpenoids by means of the Baeyer-Villiger reaction, the Beckmann rearrangement, and other oxidation processes are reviewed in this article.
Abstract: The review considers the main methods for the synthesis of derivatives of A-seco pentacyclic triterpenoids by means of the Baeyer-Villiger reaction, the Beckmann rearrangement, and other oxidation processes.
14 citations
TL;DR: In this article, a new convenient route to synthesize 1,10-seco-triterpenoids from allobetulin was demonstrated, and stereoisomerism of starting oleanane 1-oximes was determined by X-ray crystallography and additionally confirmed by the structure of obtained Beckmann rearrangement products.
3 citations
TL;DR: In this paper, a review of examples of hydroboration-oxidation of natural mono-, sesqui-, di-, and triterpenoids is presented, with a focus on di-and triterbenoids.
Abstract: Examples of hydroboration–oxidation of natural mono-, sesqui-, di-, and triterpenoids are reviewed. Diborane, BH3·THF, BH3·Me2S, disiamylborane, thexylborane, dicyclohexylborane, 9-borabicyclo[3,3,1]nonane (9-BBN), and diisopinocampheylborane are used as the hydroboration reagents; H2O2 mixed with KOH, NaOH, and NaOAc, as the oxidants. Most of the examples address mono- and sesquiterpenoids with far fewer describing di- and triterpenoids.
2 citations
TL;DR: Using combined chromatographic methods, two new compounds were isolated from the methanol extract of the leaves of Glochidion obliquum Decne and their structures were elucidated by 1D- and 2D-NMR spectra and in comparison with those reported in the literature.
Abstract: Using combined chromatographic methods, two new compounds, 6β,9β:9,13-diepoxymegastig-4-en-3β-ol (1), 5a,6a-epoxy D:C-friedoolean-8-en-3β-ol (2) were isolated from the methanol extract of the leaves of Glochidion obliquum Decne. Their structures were elucidated by 1D- and 2D-NMR spectra and in comparison with those reported in the literature.
1 citations
Cites background from "Preparation and Conformational Stud..."
...5 Hz, suggested the -configuration of epoxy group, compared with 5α,6α-epoxylupane-3β,28-diol [6], and further confirmed by NOESY correlation between H-6 (δH 3....
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10 Jun 2020
TL;DR: In this paper, the authors propose a framework to improve the quality of the data collected by the data collection system. But they do not consider the impact of data collection on the overall system performance.
Abstract: Реакция гидроборирования-окисления широко используется в химии терпеноидов как для доказательства структуры выделенных из природного сырья новых соединений, так и в направленном синтезе низкомолекулярных биорегуляторов. Причем большая часть известных примеров затрагивает моно- и сесквитерпены, гораздо меньшее количество – для ди- и тритерпеноидов: большинство представлено гидроборированием-окислением локализованных двойных связей, примеры для сопряженных диенов ограничены лишь гидроборированием-окислением цис-эудесма-6,11-диена, абиетиновой кислоты и ее метилового эфира.
Нами установлено, что восстановление пентациклического тритерпеноида – метилового эфира глицирретовой кислоты – диизобутилалюминийгидридом в хлористом метилене при -78 °С и последующем гидролизе в присутствии хлорида аммония протекает с образованием 3β,30-дигидрокси-18βH-олеан-9(11),12(13)-диена с выходом 90%. Показано, что гидроборирование 1,3-диеновой системы в нем 3.3 мольным избытком диборана в тетрагидрофуране сопровождается восстановлением карбоксильной функции, и после окисления системой перекись водорода–ацетат натрия образующихся органоборанов приводит к смеси (2 : 1 : 1) трех спиртов: 3β,11,30-тригидрокси-18βH-олеан-12(13)-ена, 3β,12,30-тригидрокси-18βH-олеан-9(11)-ена и 3β,9,30-тригидрокси-18βH-олеан-12(13)-ена, соответственно. Аналогичная смесь триолов получена также при гидроборировании-окислении 3β-гидрокси-18βH-олеан-9(11),12(13)-диен-30-овой кислоты. Реакции гидроборирования-окисления 3β,30-дигидрокси-18βH-олеан-9(11),12(13)-диена либо соответствующей 30-овой кислоты протекают как монопроцессы преимущественно по 9(11) двойной связи.
References
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TL;DR: Evaluation of anti-HIV activity with eight derivatives of 1 revealed that dihydrobetulinic acid was also a potent inhibitor of HIV replication, and there was no apparent correlation between anti-hIV activity and the inhibition of PKC among these compounds.
Abstract: Betulinic acid [1] and platanic acid [2], isolated from the leaves of Syzigium claviflorum, were found to be inhibitors of HIV replication in H9 lymphocyte cells. Evaluation of anti-HIV activity wich eight derivatives of 1 revealed that dihydrobetulinic acid [3] was also a potent inhibitor of HIV replication. The C-3 hydroxy group and C-17 carboxylic acid group, as well as the C-19 substituents, contribute to enhanced anti-HIV activity. The inhibitory activity of these compounds against protein kinase C (PKC) was also examined, since a correlation between anti-HIV and anti-PKC activities has been suggested. However, there was no apparent correlation between anti-HIV activity and the inhibition of PKC among these compounds
467 citations
TL;DR: This preliminary investigation demonstrates that simple modifications of the parent structure of betulinic acid can produce potentially important derivatives, which may be developed as antitumor drugs.
146 citations
TL;DR: Microorganisms were utilized as in vitro models to predict and prepare potential mammalian metabolites of this compound and the antimelanoma activities of these metabolites were evaluated with two human melanoma cell lines.
Abstract: Microbial transformation of the antimelanoma agent betulinic acid was studied. The main objective of this study was to utilize microorganisms as in vitro models to predict and prepare potential mammalian metabolites of this compound. Preparative-scale biotransformation with resting-cell suspensions of Bacillus megaterium ATCC 13368 resulted in the production of four metabolites, which were identified as 3-oxo-lup-20(29)-en-28-oic acid, 3-oxo-11α-hydroxy-lup-20(29)-en-28-oic acid, 1β-hydroxy-3-oxo-lup-20(29)-en-28-oic acid, and 3β,7β,15α-trihydroxy-lup-20(29)-en-28-oic acid based on nuclear magnetic resonance and high-resolution mass spectral analyses. In addition, the antimelanoma activities of these metabolites were evaluated with two human melanoma cell lines, Mel-1 (lymph node) and Mel-2 (pleural fluid).
78 citations
TL;DR: The stem bark of the Brazilian medicinal plant Zizyphus joazeiro C. Mart.
Abstract: The stem bark of the Brazilian medicinal plant Zizyphus joazeiro C. Mart. was phytochemically investigated. Three known compounds (betulinic, ursolic and alphitolic acid) and three new derivatives of betulinic acid, 7 beta-(4-hydroxybenzoyloxy)-betulinic acid, 7 beta-(4-hydroxy-3'-methoxybenzoyloxy)-betulinic acid and 27-(4-hydroxy-3'-methoxybenzoyloxy)-betulinic acid which showed a considerable activity against Gram-positive bacteria were isolated from the dichloromethane extract. The structures were established on the basis of NMR spectroscopy and mass spectrometry.
75 citations
TL;DR: A triterpene 3β,6β,16β-trihydroxylup-20(29)-ene, arjunolic acid, mollic acid, 3- 0 -methylquercetin and quercetrin were isolated from the leaves and roots of Combretum leprosum as mentioned in this paper.
62 citations