- Biomimetic oxidation of 3β-hydroxy-olean-12-ene and its acetoxy derivative with monooxygen donors catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides in dichloromethane
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The oxidation of 3β-hydroxy-olean-12-ene with monooxygen donors catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides in dichloromethane gives 3β,11α-dihydroxy-olean-12-ene, 3-oxo-olean-12-ene, 3,11-dioxo-olean-12-ene and 3β-hydroxy-olean-9(11),12-diene whereas the oxidation of 3β-acetoxy-olean-12-ene under similar conditions gives 11(-hydroxy-3β-acetoxy-olean-12-ene, 11-oxo-3β-acetoxy-olean-12-ene and 3β-acetoxy-olean-9(11),12-diene in moderate yields.
- Chauhan,Mohapatra,Mamta,Parkash,Azam
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p. 183 - 189
(2007/10/03)
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- TRITERPENE DIENOLS AND OTHER CONSTITUENTS FROM THE BARK OF PHYLLANTHUS FLEXUOSUS
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Phyllanthus flexuosus; Euphorbiaceae; stem bark; n-alkane derivatives; ent-3β-hydroxykaur-16-ene; triterpenes; oleanadienols; phytosterols; bergenin.Besides four known triterpenes and bergenin, ent-3β-hydroxykaur-16-ene and two oleanedienols were isolated from the stem bark of Phyllanthus flexuosus.The bark also contained n-alkanes, n-alkanols and phytosterols.
- Tanaka, Reiko,Matsunaga, Shunyo
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p. 2273 - 2278
(2007/10/02)
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- Reduction of Steroid and Triterpenoid α,β-Unsaturated Ketones with Lithium/Ethylenediamine
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Reduction of less sterically hindered ketone, glochidone (1) with lithium/ethylenediamine (Li/EDA) leads to the reduction of the double bond followed by that of the carbonyl group to afford thermodynamically stable alcohol, lupanol (1b).The sterically hindered α,β-unsaturated ketones such as 11-keto-triterpenoids also furnish saturated alcohols but in small proportions; the other compounds formed are obtained with reduction of the carbonyl group accompanied by dehydration or even deoxygenation.
- Pradhan, Bhim Prasad,Chakraborty, Satyajit
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p. 263 - 265
(2007/10/02)
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- A New Triterpene from Vellozia compacta
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A triterpene not previously obtained from natural sources has been isolated from Vellozia compacta and its structure assigned on the basis of spectral data.For confirmation of this assignment, a partial synthesis was carried out. β-Amyrenyl acetate was oxidized and the resulting ketone reduced to a diol, which, after selective dehydration and reoxidation, furnished the natural product.Keywords - Vellozia compacta; Velloziaceae; triterpene; oleanane; partial synthesis.
- Barnes, Roderick A.,Pereira, Anibal L.,Scofield, Tereza Cristina V.,Filho, Raimundo Braz,Pinto, Angelo C.
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p. 3674 - 3677
(2007/10/02)
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- Triterpenes of Diospyros peregrina Gurke: Partial Synthesis of Olean-9(11),12-dien-3-one and Ursan-9(11),12-dien-3-one (Marsformosanone)
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Petrol extract of the fruits of Diospyros peregrina (Ebenaceae) has afforded a pentacyclic triterpene ketone with a homoannular diene system, besides betulin and lupeol.In order to establish the structure of the ketone, partial synthesis of both olean- and ursan-9(11),12-dien-3-ones have been achieved.The structure of the pentacyclic triterpene ketone has been established as marsformosanone (II) from spectral data, chemical reactions and synthesis.The occurrence of marsformosanone in Marsdenia formosana Masamune has been recently reported .
- Bhaumik, Tapanjyoti,Dey, A. K.,Das, P. C.,Mukhopadhyay, A. K.,Chatterjee, A.
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p. 664 - 668
(2007/10/02)
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