- Synthesis and characterization of some new 1,2,3-thiadiazole and 1,2,3-selenadiazole triterpene derivatives from allobetulone and 2-oxoallobetulin
-
The synthesis of new 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives from triterpenoid ketones has been investigated via the corresponding semicarbazones. The intermediates 5, 8 have also been isolated, separated and their structures identified. The Hurd–Mori reaction and Lalezari method have been applied to synthesize a series of new substances 6 and 7. The regioselectivity of the functionalization mostly was centered at the C-3 position for the products 9 and 10. The structures of these compounds were confirmed by 2D-NMR spectroscopy.
- Dinh Ngoc, Thuc
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p. 1665 - 1671
(2020/04/30)
-
- Synthesis of 1,2-azole derivatives on the basis of α,β-unsaturated triterpene aldehydes
-
[Figure not available: see fulltext.] α,β-Unsaturated lupane and 19β,28-epoxy-18α-oleanane aldehydes were used in the synthesis of triterpenoids bearing substituted 1,2-azole moieties (1-acetyl-3-methyl-4,5-dihydro-1H-pyrazole and 3-methyl-4,5-dihydroisoxazole) at the rings А and Е. The route of synthesis for these 1,2-azole derivatives of triterpenes included an aldol condensation of α,β-unsaturated aldehydes with acetone, the products of which (α,β-unsaturated methyl ketone and β-hydroxy ketone) underwent a further cycloaddition reaction with acetylhydrazide and hydroxylamine. Cytotoxic activity studies of the synthesized compounds against seven cancer cell lines (Hep-2, HCT116, MS, RD TE32, A549, MCF-7, and PC-3) showed that the highest cytotoxicity (IC50 0.66–11.97 μM) against all tested cell lines was exihbited by 19β,28-epoxy-18α-oleanane aldehyde and the products of its condensation reactions with acetone and acetylhydrazide.
- Nazarov, Mikhail A.,Tolmacheva, Irina A.,Eroshenko, Daria V.,Maiorova, Olga A.,Dmitriev, Maksim V.,Grishko, Victoria V.
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p. 1321 - 1328
(2020/11/18)
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- Betulinol derivative and hydrophilic modification product thereof, nano solution and preparation method of nano solution
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The invention relates to a betulin derivative and a hydrophilic modification product thereof, and a nano solution and a preparation method thereof, wherein the betulin derivative is a product obtainedby an esterification reaction of the 3-hydroxyl of betulin or the derivative thereof and the carboxyl in a benzoic acid derivative, the hydrophilic modification product is dispersed in water, a metalhydroxide salt is added, stirring is performed for 30-300 minutes at 25-90 DEG C, naturally cooling is performed to room temperature so as to make the compound form a carboxyl metal salt, a surfactant accounting for 0.1-10% of the volume of the reaction system is added, and ultrasonic treatment is performed for 0-60 min to obtain the nano colloid aqueous solution of the hydrophilic modification product of betulin and derivatives thereof, wherein the nano colloid aqueous solution is good in dispersity, ideal in particle size range and easy to absorb by organisms.
- -
-
Paragraph 0076; 0090-0095
(2020/11/09)
-
- Antiviral compound, preparation and synthesis method thereof
-
The invention discloses a compound for inhibiting a virus silencing suppressor, and a synthesis method thereof, and a preparation, and belongs to the pharmaceutical technology, wherein the structure of the compound is represented by a formula (I).
- -
-
Paragraph 0060-0063
(2020/11/09)
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- The synthesis of α,β-unsaturated 18αH,19βH-ursane methyl ketones
-
An efficient and facile synthetic technique of a new α,β-unsaturated ketones of 18αH,19βH-ursane type from betulin and a possibility of their further heterocyclization to C20 pyrazoline derivative are reported. The synthetic scheme involves aldol condensa
- Nazarov, Mikhail A.,Tolmacheva, Irina A.,Grishko, Victoria V.
-
p. 267 - 276
(2020/02/13)
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- Allobetulin Ring A Contraction Effected by Sulfur Diethylaminotrifluoride
-
The action of sulfur diethylaminotrifluoride on 19β,28-epoxyoleanan-3-ol (allobetulin) causes dehydration of the terpenoid and isomerization of the ring A via its contraction to isopropylcyclopentene ring resulting in 19β,28-epoxy-A-neo-18α-olean-3(5)-ene (α-allobetulin) in a high yield.
- Fedorov,Samoilenko,Shafeeva,Abzianidze,Trishin, Yu. G.
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p. 1948 - 1950
(2018/11/24)
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- Pd-catalyzed synthesis of 2-alkynyl derivatives of 19β,28-epoxy-18α-olean-1-en-3-one
-
Basing on Sonogashira reaction of 2-iodo-19β,28-epoxy-18α-olean-1-en-3-one with alkynes an effective approach was developed to the synthesis of 2-alkynyl derivatives of 19β,28-epoxy-18α-olean-1-en-3-one. Initial 2-iodo-19β,28-epoxy-18α-olean-1-en-3-one was obtained by isomerization of the accessible betulin into allobetulin in the presence of Amberlyst 15, oxidation of allobetulin to 19β,28-epoxy-18α-olean-1-en-3-one under the action of 2-iodoxybenzoic acid, and iodination of the obtained enone in the presence of DMAP.
- Shakhmaev,Sunagatullina, A. Sh.,Abdullina,Zorin
-
p. 1705 - 1709
(2017/12/29)
-
- Synthesis of Allobetulin Using Phenylthiourea
-
A new method for preparing allobetulin via thermal rearrangement of betulin in the presence of phenylthiourea without using acidic reagents was found.
- Mamaeva,Kalieva,Tashenov,Bakibaev,Nurpeiis,Zamanova
-
p. 904 - 906
(2017/10/07)
-
- Sugar migration induced by the Wagner-Meerwein rearrangement of 28-O-glycosyl-betulin derivatives
-
Treatment of betulin-type saponins, in which the sugar moiety is connected at the 28-position, with TMSOTf affords 3-O-substituted allobetulin saponins. This unprecedented migration of the sugar part is driven by the Wagner-Meerwein rearrangement of the betulin core. According to our mechanistic studies an oxocarbenium ion released during the rearrangement reacts with the free 3-OH group of the triterpene affording the final allobetulin saponin. Migration rate depends on the size and configuration of the sugar moiety.
- Korda, Anna,Pakulski, Zbigniew,Cmoch, Piotr,Gwardiak, Katarzyna,Karczewski, Romuald
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p. 1740 - 1744
(2017/03/08)
-
- Lupane and 18α-oleanane derivatives substituted in the position 2, their cytotoxicity and influence on cancer cells
-
Lupane derivatives containing an electronegative substituent in the position 2 of the skeleton are often cytotoxic, however, the most active compounds are not selective enough. To further study the influence of a substituent in the position 2 in lupane and 18α-oleanane derivatives on their biological properties, we prepared a set of 38 triterpenoid compounds, 19 of them new, most of them substituted in the position 2. From betulin, we obtained 2-bromo dihydrobetulonic acid and 2-bromo allobetulon and their substitutions yielded derivatives with various substituents in the position 2 such as amines, amides, thiols, and thioethers. Nitration of allobetulon and dihydrobetulonic acid gave 2-nitro and 2,2-dinitro derivatives. Fifteen derivatives had IC50 50 4.6 μM and caused significant block of the tumor cells in S and slightly in G2/M transition and caused strong inhibition of DNA and RNA synthesis at 5 × IC50. 2-Amino allobetulin is the most active derivative of 18α-oleanane skeletal type prepared in our research group to date.
- Borkova, Lucie,Gurska, Sona,Dzubak, Petr,Burianova, Renata,Hajduch, Marian,Sarek, Jan,Popa, Igor,Urban, Milan
-
p. 120 - 131
(2016/06/06)
-
- Simple structural modifications confer cytotoxicity to allobetulin
-
Abstract A variety of allobetulin derivatives was synthesized from allobetulin or allobetulone. These compounds were screened for their cytotoxic activity using a photometric SRB assay employing six different human tumor cell lines. In summary, opening of
- Heller, Lucie,Obernauer, Anja,Csuk, René
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p. 3002 - 3012
(2015/08/03)
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- Allobetulin derived seco-oleananedicarboxylates act as inhibitors of acetylcholinesterase
-
Ring opening of allobetulone gave either seco-acid 8 or di-acid 4. These acids were converted into esters that were screened by Ellman's assay. A dibutenylester of low cytotoxicity (NIH 3T3 murine embryonic fibroblasts) was shown to be a good mixed-type inhibitor (Ki = 3.39, Ki′ = 2.26 μM) for acetylcholinesterase.
- Heller, Lucie,Schwarz, Stefan,Obernauer, Anja,Csuk, René
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p. 2654 - 2656
(2015/06/08)
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- Heterocycle-fused lupane triterpenoids inhibit Leishmania donovani amastigotes
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The synthesis of heterocyclic betulin derivatives and their activity against Leishmania donovani is reported. Betulonic acid was used as a versatile intermediate. Several different fused heterocycles were introduced at the 2,3-position of the lupane skeleton including isoxazole, pyrazine, pyridine, indole and pyrazole rings. Also the 28-position was modified. Three compounds, 5, 8 and 25, showed low micromolar activity with IC50 values of 13.2, 4.3 and 7.2 μM, respectively. Compound 8 showed the best activity and selectivity, and its activity was tested on infected macrophages using a concentration, 5 μM, where no macrophage toxicity was exhibited. Interestingly, the activity of compound 8 on axenic amastigotes and Leishmania-infected macrophages was similar.
- Haavikko, Raisa,Nasereddin, Abedelmajeed,Sacerdoti-Sierra, Nina,Kopelyanskiy, Dmitry,Alakurtti, Sami,Tikka, Mari,Jaffe, Charles L.,Yli-Kauhaluoma, Jari
-
p. 445 - 451
(2014/04/17)
-
- Antineoplastic agents. 595. structural modifications of betulin and the X-ray crystal structure of an unusual betulin amine dimer1
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The lupane-type triterpene betulin (1) has been subjected to a series of structural modifications for the purpose of evaluating resultant cancer cell growth inhibitory activity. The reaction sequence 7 11 12 was especially noteworthy in providing a betulin-derived amine dimer. Other unexpected synthetic results included the 11 and 13/1417 conversions, which yielded an imidazo derivative. X-ray crystal structures of dimer 12 and intermediate 25 are reported. All of the betulin modifications were examined for anticancer activity against the P388 murine and human cell lines. Significant cancer cell growth inhibition was found for 4, 8, 9, 15/16, 19, 20, 24, and 26, which further defines the utility of the betulin scaffold.
- Pettit, George R.,Melody, Noeleen,Hempenstall, Frank,Chapuis, Jean-Charles,Groy, Thomas L.,Williams, Lee
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p. 863 - 872
(2014/05/20)
-
- Inhibitory effect of the natural product betulin and its derivatives against the intracellular bacterium Chlamydia pneumoniae
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Chlamydia pneumoniae is a universal pathogen that has been indicated to play a part in the development of asthma, atherosclerosis and lung cancer. The complete eradication of this intracellular bacterium is in practice impossible with the antibiotics that are currently in use and studies on new antichlamydial compounds is challenging because Chlamydia research lacks the tools required for the genetic modification of this bacterium. Betulin is a natural lupane-class triterpene derived from plants with a wide variety of biological activities. This compound group thus has wide medical potentials, and in fact has been shown to be active against intracellular pathogens. For this reason, betulin and its derivatives were selected to be assayed against C. pneumoniae in the present study.Thirty-two betulin derivatives were assayed against C. pneumoniae using an acute infection model in vitro. Five promising compounds with potential lead compound characteristics were identified. Compound 24 (betulin dioxime) gave a minimal inhibitory concentration (MIC) of 1μM against strain CWL-029 and showed activity in nanomolar concentrations, as 50% inhibition was achieved at 290nM. The antichlamydial effect of 24 was confirmed with a clinical isolate CV-6, showing a MIC of 2.2μM. Previous research on betulin and its derivatives has not identified such a remarkable inhibition of Gram-negative bacterial growth. Furthermore, we also demonstrated that this antichlamydial activity was not due to PLA2 (EC 3.1.1.4) inhibition caused by the betulin derivatives.
- Salin, Olli,Alakurtti, Sami,Pohjala, Leena,Siiskonen, Antti,Maass, Viola,Maass, Matthias,Yli-Kauhaluoma, Jari,Vuorela, Pia
-
experimental part
p. 1141 - 1151
(2011/10/31)
-
- Synthesis of new olean-18(19)-ene derivatives from allobetulin
-
New olean-18(19)-ene triterpenoids were effectively synthesized by the interaction of allobetulin or its acetate with hosphorous oxychloride in refluxing pyridine. The structures of the synthesized 17-chlo- romethyloleane-18(19)-enes were confirmed by MR spectroscopy and X-ray analysis. Pleiades Publishing, Ltd., 2010.
- Kazakova,Khusnutdinova,Tolstikov,Suponitsky
-
experimental part
p. 512 - 515
(2011/06/19)
-
- Betulin and ursolic acid synthetic derivatives as inhibitors of Papilloma virus
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The synthesis of new betulin and ursolic acid derivatives and evaluation of their antiviral activity in vitro is reported. Betulin was modified at positions C-3, C-20 and C-28 to afford the derivatives with nicotinoyl-, methoxycynnamoyl-, alkyne and aminopropoxy-2-cyanoethyl-moieties. The two stage conversion of betulin to the new ursane-type triterpenoid by treatment of allobetulin with Ac2O-HClO4 is suggested. Cyanoethylation of ursonic acid oxime led to cyanoethyloximinoderivative. According to the results of antiviral screening against human papillomavirus type 11 the selectivity index for tested triterpenoids has a range from 10 to 35 with no cellular cytotoxicite, the most remarkable activity was found for 3β,28-di-O-nicotinoylbetulin. 3β,28-Dihydroxy-29-norlup-20(30)-yne was also active against HCV replicon (EC50 1.32; EC90 16.82; IC50 12.41; IC90 >20; SI50 9.4; SI90 >1.19). 28-O-Methoxycynnamoylbetulin was active against influenza type A virus (H1N1) (Ye{cyrillic}S{cyrillic}50 2; IC50 >200; SI >100).
- Kazakova, Oxana B.,Giniyatullina, Gul'nara V.,Yamansarov, Emil Yu.,Tolstikov, Genrikh A.
-
scheme or table
p. 4088 - 4090
(2010/08/06)
-
- Bismuth triflate-catalyzed Wagner-Meerwein rearrangement in terpenes. Application to the synthesis of the 18α-oleanane core and A-neo-18α-oleanene compounds from lupanes
-
The use of bismuth(III) salts as catalysts for the Wagner-Meerwein rearrangement of lupane derivatives with expansion of ring E and formation of an additional O-containing ring is reported. This process has also been extended to other terpenes, such as the sesquiterpene (-)-caryophyllene oxide. When the reaction was performed with oleanonic acid, 28,13β-lactonization occurred, without Wagner-Meerwein rearrangement. Under more vigorous reaction conditions, dehydration of the 3β-hydroxyl group and subsequent additional Wagner-Meerwein rearrangement led to the selective synthesis of A-neo-18α-oleanene compounds, in very high yields. The Royal Society of Chemistry 2009.
- Salvador, Jorge A. R.,Pinto, Rui M. A.,Santos, Rita C.,Le Roux, Christophe,Beja, Ana Matos,Paixao, Jose A.
-
scheme or table
p. 508 - 517
(2009/07/18)
-
- TRITERPENES DERIVATIVES AND USES THEREOF AS ANTITUMOR AGENTS OR ANTI-INFLAMMATORY AGENTS
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A compound of formula (1): wherein R1 is selected from the group consisting of H, α-L-Rhamnopyranose, α-D-Mannopyranose, β-D-Xylopyranose, β-D-Glucopyranose, and α-D-Arabinopyranose; R2 is selected from CH3, COOH, CH2OH, COOCH3 and CH2O-α-D-Arabinopyranose; with the proviso that the compound of formula (I) is not a compound of formula (I) wherein R1 is β-D-Glucopyranose and R2 is COOH; wherein R1 is α-L-Rhamnopyranose and R2 is CH3; wherein R1 is β-D-Glucopyranose and R2 is CH2OH; wherein R1 is β-D-Xylopyranose and R2 is CH2OH; wherein R1 is α-L-Rhamnopyranose and R2 is COOCH3, wherein R1 is H and R2 is CH3; wherein R1 is H and R2 is CH2OH; wherein R1 is H and R2 is COOH; or wherein R1 is H and R2 is COOCH3, or a pharmaceutically acceptable salt thereof.
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-
Page/Page column 10-11
(2008/12/06)
-
- Synthesis of 19β,28-epoxy-23,24-dinor-A-neo-18α-olean-4-en-3-one from betulin
-
19β,28-Epoxy-23,24-dinor-A-neo-18α-olean-4-en-3-one was obtained from betulin in a total yield of 18%.
- Medvedeva,Flekhter,Kukovinets,Galin,Tolstikov,Baglin,Cave
-
p. 835 - 837
(2008/09/18)
-
- Synthesis and structure-activity relationship study of cytotoxic germanicane- and lupane-type 3β-O-monodesmosidic saponins starting from betulin
-
Germanicane-type triterpenes allobetulin (3) and 28-oxoallobetulin (4) can be obtained by the Wagner-Meerwein rearrangement of the more available lupane-type triterpenes betulin (1) and betulinic acid (2), respectively. The medical uses of betulinic acid (2) and its derivatives are limited because of their poor hydrosolubility and pharmacokinetics properties. In order to overcome this major problem, we synthesized and studied the in vitro anticancer activity of a series of 3β-O-monodesmosidic saponins derived from betulin (14-16), betulinic acid (20-22), allobetulin (23-28) and 28-oxoallobetulin (29-34) based on six different natural sugar residues (d-glucose, l-rhamnose, d-arabinose, d-galactose, d-mannose and d-xylose). This structure-activity relationship study confirmed that betulinic acid saponins are generally better in vitro anticancer agents than those derived from betulin with the exception of betulin 3β-O-α-d-mannopyranoside (15) which exerted a potent cytotoxic activity against lung carcinoma (A-549) and colorectal adenocarcinoma (DLD-1) human cell lines with IC50 ranging from 7.3 to 10.1 μmol/L. Furthermore, although the synthesis of novel germanicane-type saponins was carried out with success, the bioactivity measured for these glycosides was not as high as we anticipated since only the 3β-O-β-d-glucopyranoside and 3β-O-β-d-galactopyranoside of allobetulin (23, 24) showed moderate anticancer activity (IC50 30-40 μmol/L).
- Thibeault, Dominic,Gauthier, Charles,Legault, Jean,Bouchard, Jimmy,Dufour, Philippe,Pichette, Andre
-
p. 6144 - 6157
(2008/03/28)
-
- SUBSTITUTED TARAXASTANES USEFUL FOR TREATING VIRAL INFECTIONS
-
Substituted taraxastanes useful for treating viral infections, are provided herein. Thus, in a first aspect, the invention provides compounds of Formula I and the pharmaceutically acceptable salts thereof, wherein the variables R1, R2, and X are defined herein. The compounds described herein are thought to act by inhibiting retroviral maturation, including maturation of encapsulated retroviruses viruses, such as the HIV viruses, HIV-1 and HIV-2. Pharmaceutical compositions comprising such compounds of Formula I are included herein. Methods of using such compounds to treat human patients infected with an HIV virus and reducing the mortality of AIDS are also provided herein.
- -
-
Page/Page column 12-13
(2008/06/13)
-
- Fluorination of betulinines and other triterpenoids with DAST
-
Betulinines are lupane, des-E-lupane, 18-lupene, 20(29)-lupene and 18α-oleanane derivatives with antitumor activity. We examined fluorination of these derivatives using diethylaminosulfur trifluoride (DAST) as fluorinating agent. We prepared 19β,28-epoxy-2,2-difluoro-18α- oleanan-3-one (3c), 19β,28-epoxy-2,2-difluoro-18α-oleanan-3β-ol (4a), methyl 3β-acetoxy-30-fluorolup-20(29)-ene-28-oate (6b), 3β,28-diacetoxy-22-oxo-21,21-difluorolup-18-ene (8b) and several other fluorinated betulinines for in vitro cytotoxicity tests which failed to demonstrate significant anticancer activity so far.
- Biedermann, David,Sarek, Jan,Klinot, Jiri,Hajduch, Marian,Dzubak, Petr
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p. 1157 - 1163
(2007/10/03)
-
- Therapeutic method to treat herpes virus infection
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A therapeutic method is provided for treating a mammal afflicted with a herpesvirus infection, comprising administering an effective amount of a compound of formula I: wherein R1-R11, have any of the values disclosed in the specification; or a pharmaceutically acceptable salt thereof. The invention also provides novel compounds of formula I, and pharmaceutical compositions comprising compounds of formula I.
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-
-
- Triterpenes having antibacterial activity
-
Methods of treating a bacterial infection and of killing or inhibiting bacteria are disclosed. The methods use derivatives of triterpenes that are abundant in birch bark and other plants. The triterpenes include betulin, allobetulin, and lupeol.
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-
-
- Triterpenes having human antifungal and antiyeast activity
-
Methods of treating a fungal or yeast infection and of killing or inhibiting fungi or yeast are disclosed. The methods use derivatives of triterpenes that are abundant in birch bark and other plants. The triterpenes include betulin, allobetulin, and lupeol.
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-
-
- Synthesis of betulin derivatives with solid supported reagents
-
Betulin-allobetulin transformation is effected with ferric nitrate or ferric chloride adsorbed onto silica gel or alumina, in excellent yields. In addition, allobetulin can be converted to allobetulone with silica adsorbed ferric nitrate or to 19β,28-epoxy-A-neo- 18α-olean-3(5)-ene and 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-ene with silica or alumina adsorbed ferric chloride.
- Lavoie,Pichette,Garneau,Girard,Gaudet
-
p. 1565 - 1571
(2007/10/03)
-
- Synthesis of quinoxalines fused with triterpenes, ursolic acid and betulin derivatives
-
Oxidation of triterpenoids methyl ursonate, acetylbetulone, and allobetulone with atmospheric oxygen in the presence of ButOK in ButOH afforded the corresponding 2,3-diketo derivatives in 90-97% yields. These derivatives exist predominantly as tautomers containing the enolized keto group at the C(2) atom. Their reactions with o-phenylenediamine gave rise to the corresponding quinoxalines in 85-95% yields.
- Korovin,Tkachev
-
p. 304 - 310
(2007/10/03)
-
- Simple synthesis of allobetulin, 28-oxyallobetulin and related biomarkers from betulin and betulinic acid catalysed by solid acids
-
Allobetulin (3a) and allobetulin acetate (3b) were efficiently prepared in excellent yield from betulin (2a) and betulin 3-acetate (2b) catalysed by a number of solid acids in refluxing dichloromethane. Sulfuric acid on silica, montmorillonite clays (both K10 and KSF), kaolinite, bleaching clay and toluene-p-sulfonic acid on silica are efficient catalysts for these conversions. Similarly, 28-oxyallobetulin (3c) and 28-oxyallobetulin acetate (3d) were obtained in good and excellent yield from betulinic acid (2c) and betulinic acid acetate (2d) respectively catalysed by montmorillonite K10. Two allobetulin related biomarkers, 19β,28-epoxy-A-neo-18α-olean-3(5)-ene (4a) and A-neo-18α-olean-3(5)-en-28→19β-olide (4b) were synthesised either from 3a and 3c or directly from 2a and 2c in refluxing benzene or cyclohexane catalysed by montmorillonite K10. Two other biomarkers, 19β,28-epoxy-18α-olean-2-ene (10a) and 18α-olean-2-en-28→19β-olide (10b) were also synthesised based on the above transformations. The direct formation of allobetulane related biomarkers from natural betulin 2a and betulinic acid 2c catalysed by clay mineral (montmorillonite) is of great geochemical interest.
- Li, Tong-Shuang,Wang, Jian-Xin,Zheng, Xue-Jing
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p. 3957 - 3965
(2007/10/03)
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- Oleanane triterpenoids functionalized at C-25 and C-26
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Reaction of 25-oximino-19β,28-epoxy-18α-oleanan-2β-ol (4) with nitrous acid afforded hemiacetal 22 ((25S)-2β,25;19β,28-diepoxy-18α-oleanan-25-ol). Functionalization of 19β,28-epoxy-18α-oleanan-2β-ol (1) with lead(IV) acetate gave 2β,25;19β,28-diepoxy-18α-oleanane (31). A series of derivatives with an oxygen functionality at position 25 has been prepared by modification of the functional groups in compounds 22 and 31. 26-Oximino-19β,28-epoxy-18α-oleanan-2β-ol (7) on reaction with nitrous acid afforded the corresponding nitrimine 10 which could not be converted into derivatives with an oxygen group at C-26: all the attempted preparations led invariably to compounds containing a nitrile group in position 8β. The nitrile groups in positions 10β and 8β appeared to be extremely unreactive.
- Sejbal, Jan,Klinot, Jiri,Budesinsky, Milos
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p. 1360 - 1370
(2007/10/03)
-
- PHOTOLYSES AND PYROLYSES OF TRITERPENOID NITRITES
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Derivatives of 19 β, 28-epoxy-18α-oleanane and lupane with nitrosyloxy group in positions 1α, 2β, 3α, 3β, and 28 (II, V, VIII, X and XXVII, respectively) were subjected to photolysis in solution and in the crystalline state, as well as to pyrolysis.In most cases the products identified were alcohols, ketones, olefins and seco derivatives.Photolysis of 2β-nitrite V in benzene afforded the known 24- and 25-oximino derivatives XV and XVII, photolysis of 1α-nitrite II in the crystalline state led to the little stable form XIX of N-hydroxylactam XXI which in solution was easily converted into the derivative of O-acyl-N-alkylhydroxylamine XXII.Photolysis of crystalline 3β, 28-lupanediyl 3-acetate, 28-nitrite XXVII gave 28-norolefins XXX and XXXI and 13β, 28-epoxy derivative XXXII.
- Sejbal, Jan,Klinot, Jiri,Budesinsky, Milos
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p. 1732 - 1743
(2007/10/02)
-