- Denomination of 2-bromo-3-keto triterpenoids using N,N-dimethylaniline
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Reflux of 2α-bromo/2,2-dibromolupanone (1/1a), methyl 2α-bromo/2,2-dibromodihydrobetulonate (2/2a) and 2/4α-bromofriedelin (3/3a) with N,N-dimethylaniline (DMA) resulted in the formation of lupanone, methyl dihydrobetulonate and friedelin, respectively in very good yields. The products have been characterized by spectroscopic analysis [IR, NMR ( 1H and 13C) and MS] and optical rotation as well as by comparison with the data reported in literature.
- Ghosh, Pranab,Chakraborty, Prasanta
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experimental part
p. 1037 - 1039
(2012/04/04)
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- Studies on reactions of 2-bromo-3-ketotriterpenoids: Part III - Reduction of 2α-bromo and 2,2-dibromo derivatives of lupanone and methyl dihydrobetulonate with lithium aluminium hydride and sodium borohydride
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Reduction of methyl 2α-bromodihydrobetulonate/2α-bromolupanone (1/2) and methyl 2,2-dibromodihydrobetulonate/2,2-dibromolupanone (1a/2a) with LAH at room temperature results in the formation of methyl 2α-bromo-3β-hydroxydihydrobetulonate/2α-bromo-3β-hydroxylupane (3/4), methyl dihydrobetulinate/lupanol (3b,4b) and methyl 2α-bromo dihydrobetulonate/2α-bromolupanone (1/2), methyl dihydrobetulinate/lupanol (3b/4b), lupan-2β-3β-diol (5)(from 2a) respectively, while the reduction of 1/2 and 1a/2a with NaBH4 affords 3/4, 3b/4b and methyl dihydrobetulonate/lupanone (1b/2b), 3b/4b respectively.
- Pradhan, B P,Ghosh, Pranab
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p. 1178 - 1180
(2007/10/02)
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- Studies on the reactions of 2-bromo-3-ketotriterpenoids: Part III--Reaction of Li/EDA on 2α-bromo and 2,2-dibromo derivatives of lupanone and methyl dihydrobetulonate
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The reaction of lithium in ethylenediamine with 2,2-dibromo (1/1') and 2α-bromo (2/2') derivatives of lupanone (3) and methyl dihydrobetulonate (3') furnishes lupanone/methyl dihydrobetulonate (3/3') and the pyrazine derivative (4/4').
- Pradhan, Bhim Prasad,Ghosh, Pranab
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p. 1068 - 1069
(2007/10/02)
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- Oxidation of triterpenoids: Part XVI-- Oxidation of friedel-3(4)-ene with selenium dioxide and hydrogen peroxide in tertiary butanol
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The oxidation reaction of selenium dioxide containing hydrogen peroxide in t-butanol on friedel-3(4)-ene (1) has been studied.The products of oxidation are lupanone (2) and friedelan 3β, 4α-diol (3).Their structures have been fully supported by their spectral data.
- Pradhan, Bhim Prasad,Roy, Animesh,Sinha, Rajendra Prasad
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p. 1070 - 1072
(2007/10/02)
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- The synthesis of nor- and bisnorlupanes
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In course of our studies on geochemical biomarkers we required a series of lupane standards.We report here an efficient synthesis of lupane (1) in three steps from betulin (3) in an overall yield of 47.2 percent. 17β(H)-28-Norlupane (2) was obtained in 90
- Wahhab, Amal,Ottosen, Margaret,Bachelor, Frank W.
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p. 570 - 577
(2007/10/02)
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- The Reaction of Lupane and Friedo-Oleanane Type Triterpenes with m-Chloroperbenzoic Acid
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Lupane-3β,28-diol, lupan-3β-ol, and friedelan-3β-ol were treated with m-chloroperbenzoic acid (mCPBA) in refluxing chloroform to afford corresponding lactones in one step, while lupane-3β,28-diyl, diacetate, lupan-3β-yl acetate, and friedelan-3β-yl acetate to give hydroxylated or keto derivatives.Similar reaction of dendropanoxide with mCPBA yielded 6β-, 7β-, 21α-, and 22β-hydroxylated compounds.
- Tori, Motoo,Matsuda, Reiko,Sono, Masakazu,Kohama, Yoshihiro,Asakawa, Yoshinori
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p. 2103 - 2108
(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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- FUNCTIONALISATION OF UNACTIVATED METHYL GROUPS THROUGH CYCLOPALLADATION REACTIONS
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The transformation of the organopalladium compound (3) into the corresponding deuteriated, chlorinated, or oxidized derivatives (7), (8), or (9), (11), and (12) respectively, is described.The palladation of compound (9) takes place regioselectively leadin
- Baldwin, Jack E.,Jones, Richard H.,Najera, Carmen,Yus, Miguel
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p. 699 - 712
(2007/10/02)
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