- Total Syntheses of the Lignans Isolated from Schisandra Chinensis
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The total syntheses of wuweizisu C (4), gomisin J (6), gomisin N (7), and γ-schizandrin (8) having natural configuration were accomplished in a stereoselective manner.The catalytic hydrogenation or the metal mediated 1,4-reduction of the tetracyclic lactones (12, 17, 22, 30) played the significant role for the stereoselective introduction of C6, C7 dimethyl moiety.Furthermore, the neighboring carbonyl group assisted regioselective demethylation of 5 was essential for the synthesis of 6.
- Tanaka, Masahide,Ohshima, Toshihiro,Mitsuhashi, Hiroshi,Maruno, Masao,Wakamatsu, Takeshi
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p. 11693 - 11702
(2007/10/02)
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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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- Intramolecular Oxidative Coupling of Aromatic Compounds. VI. An Efficient Synthesis of Some Dibenzocyclooctene Lignans
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The 1,4-diaryl-2,3-dimethylbutanes (4) and (5) were readily prepared by reductive coupling of an arylacetone precursor followed by hydrogenation.Intramolecular oxidative coupling (dichlorodicyanobenzoquinone/trifluoroacetic acid) gave dibenzocyclooctene derivatives in good yield. (+/-)-Deoxyschizandrin and the corresponding trans isomer, existing in two distinct conformations, were prepared.
- Carroll, Anthony R.,Taylor, Walter C.
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p. 937 - 942
(2007/10/02)
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- Intramolecular Oxidative Coupling of Aromatic Compounds. VII. A Convenient Synthesis of (+/-)-Deoxyschizandrin
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A convenient synthesis of (+/-)-deoxyschizandrin was achieved through the key step of reductive coupling of the bisacetonylbiphenyl (3).The latter compound was synthesized by oxidative cleavage of the bis olefin (5) formed by Claisen rearrangement of the bismethallyl ether of 2,2',4,4'-tetramethoxybiphenyl-3,3'-diol.The synthesis of 2,2',4,4'-tetramethoxy-6,6'-di(prop-1-enyl)biphenyl-3,3'-diol (2) is also described.The diphenolic oxidation of (2) did not lead to products with β,β' carbons linked.
- Carroll, Anthony R.,Read, Roger W.,Taylor, Walter C.
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p. 1579 - 1590
(2007/10/02)
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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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- NEOLIGNANS FROM LICARIA AUREA
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Key Word Index - Licaria aurea; Lauraceae; diaryltetrahydrofuran neolignans; β-aryloxy-arylpropane neolignans.Abstract - The fruit calyces of Licaria aurea were found to contain the diaryltetrahydrofuran type neolignans grandisin, de-O-methylgrandisin and dide-O-methylgranidisin, as well the β-aryloxy-arylpropane type neolignans virolongin A and virolongin B.
- Barbosa-Filho, Jose M.,Silva, Marcelo S. da,Yoshida, Massayoshi,Gottlieb, Otto R.
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p. 2209 - 2211
(2007/10/02)
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- Syntheses of (+/-)-Deoxyschizandrin and the Lignan, 1,4-Bis(3,4-dimethoxyphenyl)-2,3-dimethylbutane
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(+/-)-Deoxyschizandrin (1) has been synthesised through a dimerisation reaction as a key step.The Grignard reagent from 1-(3,4,5-trimethoxyphenyl)-2-bromopropane (10) on reaction with 2-t-butyl-3-phenyloxaziridine gives 1,4-bis(3,4,5-trimethoxyphenyl)-2,3-dimethylbutane (11), which is cyclised using vanadium oxytrifluoride to get deoxyschizandrin (1).Following the above methodology, 1,4-bis(3,4-dimethoxyphenyl)-2,3-dimethylbutane (2), a lignan has also been prepared.
- Gunasekaran, A.,Balasubramanian, K.
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p. 308 - 310
(2007/10/02)
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- A LIGNAN FROM SCHIZANDRA CHINENSIS
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A new dibenzocyclooctadiene lignan, isoschizandrin was isolated from the fruits of Schizandra chinensis.The structure was elucidated on the basis of the spectral analysis and chemical correlation with schizandrin and (+)-deoxyschizandrin.In experiments using rats, schizandrin and its derivatives, including isoschizandrin, showed inhibitory effects on stress-induced gastric ulceration (p.o).Key Word Index-Schizandra chinensis; Schizandraceae; dibenzocyclooctadiene; lignan; isoschizandrin; anti-ulcer effect.
- Ikeya, Yukinobu,Taguchi, Heihachiro,Mitsuhashi, Hiroshi,Takeda, Shigefumi,Kase, Yoshio,Aburada, Masaki
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p. 569 - 574
(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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- THE CONSTITUENTS OF SCHIZANDRA CHINENSIS BAILL. VI. 13C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY OF DIBENZOCYCLOOCTADIENE LIGNANDS.
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The 13C NMR spectra of thirteen dibenzocyclooctadiene lignans, isolated from the truits of Schizandra chinensis BAILL. (Schizandraceae), were analyzed and their carbon shifts assigned.Several important chemical shift trends are described.Keywords - Schizandra chinesis BAILL.; Schizandraceae; dibenzocyclooctadiene; lignans; Gomisins; 13C NMR
- Ikeya, Yukinobu,Taguchi, Heihachiro,Sasaki, Hiroshi,Nakajima, Kaoru,Yosioka, Itiro
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p. 2414 - 2421
(2007/10/02)
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