526-06-7Relevant academic research and scientific papers
Stereoselective total synthesis of furofuran lignans through dianion aldol condensation
Jung, Jae-Chul,Kim, Ju-Cheun,Moon, Hyung-In,Park, Oee-Sook
, p. 6433 - 6437 (2007/10/03)
Highly stereoselective total synthesis of (+)-eudesmin, (+)-yangambin, (-)-eudesmin, and (-)-yangambin is described. This method is useful to generate the core skeleton of furofuran rings utilizing modification of Evans asymmetric aldol condensation.
Sesquineolignans and other constituents from the seeds of Joannesia princeps
Waibel, Reiner,Benirschke, Gerd,Benirschke, Monika,Achenbach, Hans
, p. 805 - 811 (2007/10/03)
From the as extract of the seeds of the Brazilian Joannesia princeps 3,3′-bisdemethylpinoresinol and six new sesquineolignans were isolated besides the known neolignans americanol A, isoamericanol A and isoamericanin A which were found to be the major constituents. A method was developed to distinguish americanol- from isoamericanol-type compounds spectroscopically.
Stereoselective intramolecular coupling of diaroylacetates of (1R,1′R)-exo,exo′-3,3′-biisoborneol by oxidation with Br 2
Kise, Naoki,Fujimoto, Azumi,Moriyama, Noriaki,Ueda, Nasuo
, p. 2495 - 2497 (2007/10/03)
The oxidative coupling of diaroylacetate derivatives prepared from (1R,1′R)-exo,exo′-3,3′-biisoborneol with NaH-Br2 gave the corresponding intramolecularly coupled products stereoselectively. The major (R,R)-isomers thus obtained were transformed to (-)-Sesamin and (-)-Eudesmin.
Short and stereoselective total synthesis of furano lignans (±)-dihydrosesamin, (±)-lariciresinol dimethyl ether, (±)-acuminatin methyl ether, (±)-sanshodiol methyl ether, (±)-lariciresinol, (±)-acuminatin, and (±)-lariciresinol
Roy, Subhas Chandra,Rana, Kalyan Kumar,Guin, Chandrani
, p. 3242 - 3248 (2007/10/03)
Intramolecular radical cyclization of suitably substituted epoxy ethers 4a-g using bis(cyclopentadienyl)titanium(III) chloride as the radical source resulted in trisubstituted tetrahydrofurano lignans and 2,6-diaryl-3,7-dioxabicyclo [3.3.0] octane lignans depending on the reaction conditions. The titanium(III) species was prepared in situ from commercially available titanocene dichloride and activated zinc dust in THF. Upon radical cyclization followed by acidic workup, epoxy olefinic ethers 4a-g afforded furano lignans dihydrosesamin 1a, lariciresinol dimethyl ether lb, acuminatin methyl ether le, and sanshodiol methyl ether 1g directly and lariciresinol 1h, acuminatin li, and lariciresinol monomethyl ether 1j after removal of the benzyl protecting group by controlled hydrogenolysis of the corresponding cyclized products. The furofuran lignans sesamin 2a, eudesmin 2b, and piperitol methyl ether 2e were also prepared directly by using the same precursors 4a-f on radical cyclization followed by treatment with iodine and pinoresinol 2h, piperitol 2i, and pinoresinol monomethyl ether 2j after controlled hydrogenolysis of the benzyl protecting group of the corresponding cyclized products. Two naturally occurring acyclic lignans, secoisolariciresinol 5h and secoisolariciresinol dimethyl ether 5b, have also been prepared by exhaustive hydrogenolysis of 2h and 2b, respectively.
Stereoselective homocoupling of chiral 1-aroylacetyl-2-imidazolidinones by oxidation with Br2
Kise, Naoki,Fujimoto, Azumi,Ueda, Nasuo
, p. 1845 - 1847 (2007/10/03)
The oxidative coupling of sodium enolates of (4R,5S)-1-aroylacetyl-3,4-dimethyl-5-phenyl-2-imidazolidinones with Br2 as the oxidant affords the R,R-dimers stereoselectively. The R,R-selectivity can be explained by a radical coupling mechanism.
Enantioselective accumulation of (-)-pinoresinol through O- demethylation of (±)-eudesmin by Aspergillus niger
Kasahara, Hiroyuki,Miyazawa, Mitsuo,Kameoka, Hiromu
, p. 1479 - 1482 (2007/10/03)
Microbial transformation of (±)-eudesmin by Aspergillus niger was investigated. Enantioselective accumulation of (-)-pinoresinol was shown through O-demethylation of (±)-eudesmin. This fungus O-demethylated both enantiomers of eudesmin, but the conversion
Photoinduced molecular transformations. 157. A new stereo- and regioselective synthesis of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans involving a β-scission of alkoxyl radicals as the key step. New total syntheses of (±)-sesamin, (±)-eudesmin, and (±)-yangambin
Suginome,Orito,Yorita,Ishikawa,Shimoyama,Sasaki
, p. 3052 - 3064 (2007/10/02)
New total syntheses of naturally occurring 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans, (±)-sesamin and (±)-eudesmin, and the first total synthesis of (±)-yangambin were achieved according to a general method devised by Suginome and colleagues for replacing the carbonyl group of the cyclopentanone ring with an oxygen atom to give a corresponding tetrahydrofuran ring involving a regioselective β-scission of alkoxyl radicals; arylation of dimethyl, diallyl, or dibenzyl 3,7-dioxobicyclo[3.3.0]octane-2,6-dicarbonate (18 and 19a,b) with aryllead triacetate 9a-c, followed by dealkoxycarbonylation of the resulting arylated product 20a-f, gave 2,6-diaryl-3,7-dioxobicyclo[3.3.0]octane 21a-c. A regioselective Baeyer-Villiger oxidation of 21a-c with m-CPBA-NaHCO3 or -K2CO3 gave the corresponding δ-lactone 22a-c, which was reduced with DIBAL to give the corresponding lactol 23a-c. The irradiation of a solution of the hypoiodite of 23a-c, generated in situ with mercury(II) oxide-iodine, in benzene with Pyrex-filtered light resulted in a regioselective β-scission of the corresponding alkoxyl radical to give iodo formate 24a-c. Heating 24a-c in MeOH with NaBH4 gave (±)-sesamin (25a), (±)-eudesmin (25b), or (±)-yangambin (25c).
Enantioselective synthesis of natural dibenzylbutyrolactone lignans (-)-enterolactone, (-)-hinokinin, (-)-pluviatolide, (-)-enterodiol, and furofuran lignan (-)-eudesmin via tandem conjugate addition to γ-alkoxybutenolides1,2
Van Oeveren,Jansen,Feringa
, p. 5999 - 6007 (2007/10/02)
A general and efficient method is described for the asymmetric synthesis of a variety of liguans. 5-(Menthyloxy)-2(5H)-furanones 5 proved to be excellent chiral synthons in this respect and could be transformed with complete stereoselectivity into a number of lignans. The addition of lithiated dithianes 7 to enantiomerically pure butenolides 5 was followed by quenching of the resulting lactone enolate anions with a benzylbromide (9) or with an aldehyde (6). This tandem addition quenching procedure gave the diastereomerically pure adducts 11, 26, or 27 in 50-67% yield, with a carbon skeleton as found in most natural lignans. As examples of the wide applicability of this method, the syntheses of the enantiomerically pure natural lignans (-)-hinokinin (23b), (-)-enterolactone (24a), (-)-pluviatolide (24c), and (-)-enterodiol (25) in overall yields of 29-37% from 5a and (-)eudesmin (30) in 16% overall yield from 5b are described.
Asymmetric 1,4-additions to γ-menthyloxybutenolides. (Part III) Enantioselective synthesis of (-) eudesmin
Jansen,Feringa
, p. 3239 - 3242 (2007/10/02)
Based on an enantioselective Michael addition of the aryldithiane of 3,4-dimethoxybenzaldehyde, to (5S)-menthyloxy-2[5H]-furanone optically pure (-) Eudesmin was synthesized in 16% overall yield.
Effects of O-Methylation and O-Glucosylation on Carbon-13 Nuclear Magnetic Resonance Chemical Shifts of Matairesinol, (+)-Pinoresinol and (+)-Epipinoresinol
Nishibe, Sansei,Tsukamoto, Hiroki,Hisada, Sueo
, p. 4653 - 4657 (2007/10/02)
The effects of O-methylation and O-glucosylation on the carbon-13 nuclear magnetic resonance chemical shifts of matairesinol (1), (+)-pinoresinol (6) and (+)-epipinoresinol (11) are discussed.The chemical shifts of carbons on the 2,3-dibenzylated butyrolactone and 2,6-diarylated 3,7-dioxabicyclooctane rings are not affected by methylation and glucosylation of hydroxy groups on the aromatic rings.As regards the chemical shifts of aromatic carbons caused by O-methylation, all the 1'(1''),3'(3''), and 4'(4'') carbons of the guaiacyl unit are characteristically shifted downfield by 1.6+/-0.1, 1.3+/-0.1, and 2.4+/-0.1 ppm, respectively, while the 5'(5'') carbons are shifted upfield by 3.5+/-0.1 ppm.In the case of the chemical shifts of aromatic carbons caused by O-glucosylation, all the 1'(1'')and 3'(3'') carbons of the guaiacyl unit are characteristically shifted downfield by 3.0+/-0.1 and 1.3+/-0.1 ppm, respectively.Keywords - 13C-NMR; O-methylation shift; O-glucosylation shift; ligan; matairesinol; (+)-pinoresinol; (+)-epipinoresinol; guaiacyl group
