- Simple synthesis of trans-α,β-dibenzyl-γ-butyrolactone lignans by diastereoselective reduction of α-benzylidene-β-benzyl-γ-butyralactones using NaBH4-NiCl2
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trans-α,β-Dibenzyl-γ-butyrolactone lignans were synthesized by stereoselective reduction of α-benzylidene-β-benzyl-γ-butyrolactones using NaBH4-NiCl2. The reduction is found to proceed via conjugate addition of a hydride to an α-benz
- Moritani,Fukushima,Miyagishima,Ohmizu,Iwasaki
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p. 2281 - 2286
(2007/10/03)
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- Ruthenium dioxide in fluoro acid medium V. Application to the non phenolic oxidative coupling of diarylbutanes. Conformational studies of cis and trans deoxyschizandrins
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Ruthenium (IV) dioxide dihydrate in fluoro acidic medium was found to be a very efficient agent for the non phenolic oxidative coupling of diarylbutanes. We observed along with the expected aryl-aryl coupling, an unusual aryl-benzyl coupling, leading to a known class of lignans, the aryltetralins. Conformational studies of resultant cis and trans deoxyschizandrins were performed using high resolution NMR and molecular models.
- Dhal,Landais,Lebrun,Lenain,Robin
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p. 1153 - 1164
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF METHOXY SUBSTITUTED 2,3-DIBENZYL-γ-BUTYROLACTONES USING ORGANIC PHOSPHONATES AS INTERMEDIATES
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A stereoselective, short and convergent synthesis of methoxy substituted 2,3-dibenzyl-γ-butyrolactones was developed using organic phosphonates as key intermediates.
- Compagnone, Reinaldo S.,Suarez, Alirica
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- Ruthenium dioxide in fluoro acid medium: I. A new agent in the biaryl oxidative coupling. Application to the synthesis of non phenolic bisbenzocyclooctadiene lignan lactones
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Ruthenium (IV) dioxide dihydrate in fluoro acid medium was found to be a very efficient agent for the oxidative coupling of non phenolic lignans and their derivatives, and this method was applied to the total synthesis of (+/-)-neoisostegane 2a and (+/-)-steganolide A 2b. This procedure was also used to obtain the first stereospecific synthesis of a cis-bisbenzocyclooctadiene lactone, the (+/-)-deoxyschizandrin 17, of which, was afforded by a short reduction sequence.
- Landais,Robin,Lebrun
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p. 3787 - 3804
(2007/10/02)
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- A SIMPLE PREPARATION OF (R)-(+)-β-(3,4,5-TRIMETHOXYBENZYL)-BUTANOLIDE, AND ITS USE IN THE TOTAL SYNTHESES OF NATURALLY OCCURRING DIBENZYLBUTANOLIDE LIGNANS
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Resolution of methyl α-(3,4,5-trimethoxybenzyl)hemisuccinate by means of (-)-ephedrine, followed by calcium borohydride reduction, afforded (R)-(+)-β-(3,4,5-trimethoxybenzyl)butanolide.This lactone was used as a starting material for the optically active
- Lalami, Khalid,Dhal, Robert,Brown, Eric
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p. 1131 - 1134
(2007/10/02)
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- Studies on the Constituents of the Seeds of Hernandia ovigera L. VI. Isolation and Structural Determination of Three Lignans
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Three kinds of lignans, including a new lignan, named hernolactone, were isolated from the seeds of Hernandia ovigera L. besides six previously reported lignans, desoxypodophyllotoxin (DPT), desoxypicropodophyllin, bursehernin, podorhizol, hernandin and d
- Tanoguchi, Mariko,Arimoto, Masao,Saika, Hideyuki,Yamaguchi, Hideo
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p. 4162 - 4168
(2007/10/02)
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- SYNTHESIS OF DIARYLBUTANES FROM CORDIGERINES AND REINVESTIGATION OF THEIR OXIDATIVE COUPLINGS IN DEOXYSCHIZANDRINS. - AN UNUSUAL FORMATION OF PHENYLTETRALIN LIGNANS -
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Dibenzylbutanolide lignans including cordigerines were synthetized and transformed in the corresponding diarylbutane lignans which were submitted to non-phenolic oxidative coupling conditions by using RuO2 or Tl2O3 in trifluoroacetic medium to give deoxyschizandrins.A concurently aryl-benzyl coupling leads to the formation of the corresponding phenyltetralin of which the structure was confirmed by total synthesis.
- Landais, Y.,Lebrun, A.,Lenain, V.,Robin, J.-P.
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p. 5161 - 5164
(2007/10/02)
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- Lignans from Piper cubeba
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From the hot petrol extract of Piper cubeba ftuits, six lignans were isolated. Two of these, which have been obtained from a natural source for the first time, have been characterized as (2R,3R)-2-(3″,4″,5″-trimethoxybenzyl)-3-(3′,4′-methylenedioxybenzyl)-1,4-butanediol [(-)-dihydroclusin] and (3R,4R)-3,4-bis-(3,4,5-trimethoxybenzyl)tetra-hydro-2-furanol [(-)-cubebinin]. (-)Cubebin, (-)-hinokinin, (-)-clusin and (-)-dihydrocubebin were also found in this plant. Only (-)-cubebin has been reported so far from this source.
- R. Prabhu, Bharathi,B. Mulchandani, Newand
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p. 329 - 331
(2007/10/02)
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