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Synthesis of Lignans Based on a Borate-mediated One-pot Sequential Suzuki-Miyaura Coupling of Cyclic Boranes
Lignans are a group of polyphenolic phytochemicals that possess a large spectrum of chemical structures and biological activities. Here the syntheses of lignans – anwulignan, burseran, dehydroxycubebin, ruburisandrin B, and sesamin – are achieved based on a borate-mediated one-pot sequential Suzuki-Miyaura coupling of cis- and trans-fused bicyclic boranes, which were prepared by diastereoselective cyclic hydroboration of exo-cyclic diene with cyclopentyl- and thexylboranes, respectively. A one-pot sequential Suzuki-Miyaura coupling of each cyclic borate with various aryl bromides initiated by activation of the cyclic borane with the carbon nucleophile provided 2,3-dibenzylbutane derivatives with different aromatic substituents. Finally, the syntheses of naturally occurring lignans were accomplished in several steps from the products of Suzuki-Miyaura coupling.
Sato, Ko,Tanaka, Hiroshi
supporting information
p. 9422 - 9428
(2021/05/26)

Enantioselective total synthesis of furofuran lignans via Pd-catalyzed asymmetric allylic cycloadditon of vinylethylene carbonates with 2-nitroacrylates
Herein, a practical and efficient approach to tetrahydrofurans with three-stereocenters has been developed through Pd-catalyzed asymmetric allylic cycloaddition of vinylethylene carbonates (VECs) with 2-nitroacrylates under mild conditions. By using this asymmetric catalytic reaction as a key step, several furofuran lignans with stereodivergency have been effectively synthesized through 5- or 6-step sequences from readily available starting materials.
Zhao, Can,Khan, Ijaz,Zhang, Yong Jian
supporting information
p. 12431 - 12434
(2020/10/30)

Chromatography-free “two-pots” asymmetric total synthesis of (+)-sesamin and (+)-aschantin
A gram-scale chromatography-free asymmetric total synthesis of both homo- and heterobiaryl furofuran lignans containing at least one methylenedioxy phenyl unit such as (+)-sesamin and (+)-aschantin is accomplished in “two-pots” from easily accessible enantiopure lactone involving four steps in high overall yields. Steps- and pot economy are the key advantages of the protocol. Additionally, the bromo-functionality of the intermediates is useful for late stage functionalization.
Hajra, Saumen,Garai, Sujay,Sen, Biswajit
(2020/09/02)

Electochemical asymmetric dimerization of cinnamic acid derivatives and application to the enantioselective syntheses of furofuran lignans
A new electrochemical method for the asymmetric oxidative dimerization of cinnamic acid derivatives has been developed. This method enabled the enantioselective syntheses of furofuran lignans, yangambin, sesamin and eudesmin.
Mori, Naoki,Furuta, Akiko,Watanabe, Hidenori
p. 8393 - 8399
(2016/12/06)

Metal Triflates for the Production of Aromatics from Lignin
The depolymerization of lignin into valuable aromatic chemicals is one of the key goals towards establishing economically viable biorefineries. In this contribution we present a simple approach for converting lignin to aromatic monomers in high yields under mild reaction conditions. The methodology relies on the use of catalytic amounts of easy-to-handle metal triflates (M(OTf)x). Initially, we evaluated the reactivity of a broad range of metal triflates using simple lignin model compounds. More advanced lignin model compounds were also used to study the reactivity of different lignin linkages. The product aromatic monomers were either phenolic C2-acetals obtained by stabilization of the aldehyde cleavage products by reaction with ethylene glycol or methyl aromatics obtained by catalytic decarbonylation. Notably, when the method was ultimately tested on lignin, especially Fe(OTf)3 proved very effective and the phenolic C2-acetal products were obtained in an excellent, 19.3±3.2 wt % yield.
Deuss, Peter J.,Lahive, Ciaran W.,Lancefield, Christopher S.,Westwood, Nicholas J.,Kamer, Paul C. J.,Barta, Katalin,de Vries, Johannes G.
p. 2974 - 2981
(2016/11/02)

Stereocontrolled total syntheses of optically active furofuran lignans
Plant products (+)-sesamin, (+)-sesaminol, (+)-methylpiperitol, (+)-aschantin, and (+)-5'-hydroxymethylpiperitol were synthesized in a highly stereocontrolled manner through l-proline-catalyzed bifunctional-urea-accelerated cross-aldol reaction, followed by biomimetic construction of the furofuran lignan skeleton through a quinomethide intermediate.
Inai, Makoto,Ishikawa, Ryo,Yoshida, Naoto,Shirakawa, Nana,Akao, Yusuke,Kawabe, Yusuke,Asakawa, Tomohiro,Egi, Masahiro,Hamashima, Yoshitaka,Kan, Toshiyuki
p. 3513 - 3521
(2015/11/17)

Total syntheses of (+)-sesamin and (+)-sesaminol
Total syntheses of (+)-sesamin (1a ) and (+)-sesaminol (1b), which are major components of sesame lignans derived from Sesamum indicum, were accomplished in a highly stereo-controlled manner. Key steps include an L-proline-catalyzed cross-a ldol reaction, which was accelerated with the aid of bifunctional urea 7, and the construction of a furofuran lignan skeleton through a quinomethide intermediate.
Ishikawa, Ryo,Yoshida, Naoto,Akao, Yusuke,Kawabe, Yusuke,Inai, Makoto,Asakawa, Tomohiro,Hamashima, Yoshitaka,Kan, Toshiyuki
p. 1572 - 1574
(2015/02/19)

Stereospecific synthesis of endo-endo-3,7-dioxabicyclo[3.3.0]octane lignans using 1,6-bis(dipropylboryl)-2,4-hexadiene
A general methodology for the stereoselective synthesis of compounds of the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane series was developed. The strategy includes allylboration of aromatic aldehydes with 1,6-bis(dialkylboryl)-2,4- hexadiene, ozonolysis of the thus obtained 1,4-diaryl-2,3-divinyl-1,4-diols, and subsequent intramolecular cyclization. This methodology was used for obtaining the naturally occurring lignans of the furofuran series, viz., diaeudesmin, diayangambin, epiasarinin, epieudesmin, epiyangambin, and asarinin.
Anfimov,Erdyakov,Gurskii,Bubnov
p. 2336 - 2342
(2012/11/07)

METHOD AND APPARATUS FOR PRODUCING EPISESAMIN-RICH COMPOSITION
To provide a process and an apparatus by means of which a composition that contains episesamin in a concentration greater than 50 wt% on the basis of the sum weight of sesamin and episesamin can be produced conveniently and at high yield. There are provided a process and an apparatus which comprise the step of applying epimerization to sesamin or a sesamin-containing composition so that at least part of the sesamin is converted to episesamin and the step of selectively crystallizing episesamin by recrystallization and by means of which a composition that contains episesamin in a concentration greater than 50 wt% can be produced conveniently and at high yield.
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(2008/12/06)

METHOD OF PURIFYING EPISESAMIN
There is disclosed an episesamin refining method in which a mixture of sesamin components that contains sesamin, episesamin and the like is brought into contact with an aqueous medium to form a slurried mixture, and thereafter the solids are separated from the mixture or the slurried mixture is dissolved in a suitable aqueous medium under heating and, thereafter, the solution is slowly cooled to recrystallize, thereby yielding an episesamin-enriched composition with an increased relative episesamin content. By the present invention, episesamin can be conveniently and efficiently refined from a mixture of sesamin components that mainly comprises sesamin and episesamin.
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(2008/12/07)

The dihydrofuran template approach to furofuran synthesis
Flash vacuum pyrrolysis of vinyl epoxides provides cis-dihydrofuran carboxylic esters in good yields and diastereoselectivities, which, on base-promoted epimerisation afford the complementary trans series. The compounds provide a viable template for a Lewis acid promoted cyclisation to provide the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane core found in the furofuran series of natural lignans. This strategy is stereodivergent and can be controlled to provide the exo-exo, exo-endo or endo-endo stereochemistries. The approach has been exemplified in syntheses of the sesamyl furofurans (±)-epiasarinin and (±)-asarinin. The Royal Society of Chemistry 2006.
Aldous, David J.,Batsanov, Andrei S.,Yufit, Dmitrii S.,Dalenon, Anne J.,Dutton, William M.,Steel, Patrick G.
p. 2912 - 2927
(2008/02/09)

An efficient asymmetric synthesis of furofuran lignans: (+)-Sesamin and (-)-sesamin
An efficient synthesis of (+)-sesamin 1a and (-)-sesamin 1b is described. The key reactions include highly stereoselective aldol condensation of piperonal 7 with the dianion of chiral oxazolidinone 8, followed by intramolecular ring cyclization of aldol product 11 in high yield.
Kim, Ju-Cheun,Kim, Kwang-Hyun,Jung, Jae-Chul,Park, Oee-Sook
p. 3 - 6
(2007/10/03)

The epimerization of sesamin and asarinin
Sesamin (1) and asarinin (2) are two C-7′ epimeric lignans. Molecular modeling by semiempirical methods indicated that 1 is more stable than 2 by about 2.5 kcal/mol. However, epimerization under acidic conditions led to a 44.8/55.2 equilibrium ratio of 1 and 2. Single-crystal X-ray diffraction analyses indicated that 1 was monoclinic with a = 10.0435(19) A, b = 6.9151(8) A, c = 11.8460(13) A, and 2 was triclinic with a= 5.595(5) A, b = 9.5910(18) A, c = 15.620(4) A. The unexpected equilibrium ratio of 1 and 2 indicated that structural changes are dependent on the conditions of the extraction processes.
Li, Chia-Ying,Chow, Tahsin J.,Wu, Tian-Shung
p. 1622 - 1624
(2008/09/17)

Concise enantioselective synthesis of furan lignans (-)-dihydrosesamin and (-)-acuminatin and furofuran lignans (-)-sesamin and (-)-methyl piperitol by radical cyclization of epoxides
Enantioselective syntheses of furan lignans (-)-dihydrosesamin and (-)-acuminatin and furofuran lignans (-)-sesamin and (-)-methyl piperitol were achieved in up to only three steps in 43%, 42%, 63%, and 60% overall yield, respectively, with high optical purity through stereoselective intramolecular radical cyclization of suitably substituted epoxy olefinic ethers using bis(cyclopentadienyl)titanium(III) chloride as the radical initiator. The key intermediate, chiral epoxy alcohol 4, was prepared by the Sharpless kinetic resolution method. The titanium(III) initiator was prepared in situ from commercially available titanocene dichloride and activated zinc dust in tetrahydrofuran. Georg Thieme Verlag Stuttgart.
Banerjee, Biplab,Roy, Subhas Chandra
p. 2913 - 2919
(2007/10/03)

Stereoselective intramolecular coupling of diaroylacetates of (1R,1′R)-exo,exo′-3,3′-biisoborneol by oxidation with Br 2
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.
Kise, Naoki,Fujimoto, Azumi,Moriyama, Noriaki,Ueda, Nasuo
p. 2495 - 2497
(2007/10/03)

A Short Synthesis of (±)-Epiasarinin
matrix presented Epiasarinin, an endo-endo furofuran, has been synthesized from piperonal via a five-step route with good stereocontrol. The sequence involves Darzens condensation, alkenyl epoxide-dihydrofuran rearrangement, and a Lewis acid mediated cyclization.
Aldous, David J.,Dalencon, Anne J.,Steel, Patrick G.
p. 1159 - 1161
(2007/10/03)

Short and stereoselective total synthesis of furano lignans (±)-dihydrosesamin, (±)-lariciresinol dimethyl ether, (±)-acuminatin methyl ether, (±)-sanshodiol methyl ether, (±)-lariciresinol, (±)-acuminatin, and (±)-lariciresinol
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.
Roy, Subhas Chandra,Rana, Kalyan Kumar,Guin, Chandrani
p. 3242 - 3248
(2007/10/03)

A general approach to the asymmetric synthesis of lignans: (-)-methyl piperitol, (-)-sesamin, (-)-aschantin, (+)-yatein, (+)-dihydroclusin, (+)-burseran, and (-)-isostegane
A highly efficient, diastereo- and enantioselective route was developed to access a great variety of lignans. The asymmetric synthesis of the 2,3-disubstituted γ-butyrolactones 9a-c could be improved in the case of aldol reactions by employing 2.2 equivalents of LiCl as an additive to provide, after purification, highly diastereo- and enantioenriched starting materials for the synthesis of the furofuran lignans (-)-methyl piperitol, (-)-sesamin, and (-)-aschantin. Furthermore, the γ-butyrolactone 15 was converted into dibenzylbutyrolactone lignan (+)-yatein, the dibenzylbutandiol type (+)-dihydroclusin, the tetrahydrofuran type (+)-burseran, and the dibenzocyclooctadiene type (-)-isostegane.
Enders, Dieter,Lausberg, Vivien,Del Signore, Giuseppe,Berner, Otto Mathias
p. 515 - 522
(2007/10/03)

Stereoselective homocoupling of chiral 1-aroylacetyl-2-imidazolidinones by oxidation with Br2
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.
Kise, Naoki,Fujimoto, Azumi,Ueda, Nasuo
p. 1845 - 1847
(2007/10/03)

C-H insertion approach to the synthesis of endo,exo-furofuranones: Synthesis of (±)-asarinin, (±)-epimagnolin A, and (±)-fargesin
A series of novel 5-aryl-4-aryloxymethyl-3-diazotetrahydrofuran-2-ones (12, 24, and 35a/b) have been prepared and found to undergo regio- and stereoselective C-H insertion reactions to afford 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-8-ones (18, 26, and 36a/b) with endo,exo stereochemistry. Subsequent reduction of the lactone ring and cyclization of the resulting diols 27 and 37a/b permitted the synthesis of three endo, exo-furofuran lignans: asarinin (2), fargesin (3), and epimagnolin A (4). En route to the key diazo compounds 24 and 35a/b, a modified procedure for the Ghosez keteniminium-olefin cyclization was developed, which was required to minimize the decomposition of acid-sensitive functional groups such as electron-rich benzylic ethers that were present in the target compounds 2-4.
Brown,Bataille,Bruton,Hinks,Swain
p. 6719 - 6728
(2007/10/03)

A short and stereoselective total synthesis of (±)-sesamin by radical cyclisation of an epoxide using a transition-metal radical source
A short, efficient and stereoselective synthesis of a furofuran lignan, (±)-sesamin, has been achieved in good overall yield through the radical cyclisation of an epoxide using a Ti(III) reagent as the radical initiator. (C) 2000 Elsevier Science Ltd.
Rana,Guin,Roy
p. 9337 - 9338
(2007/10/03)

Clay catalysed convenient isomerization of natural furofuran lignans under microwave irradiation
The naturally occuring furofuron lignans, (+)-sesamin, (+)-eudesmin, (+)-syringaresinol and (+)-yangambin underwent rapid isomerization to their corresponding C-7 epimers under microwave irradiation in the presence of montmorillonite KSF as catalyst.
Das,Madhusudhan,Venkataiah
p. 4001 - 4006
(2007/10/03)

An efficient and highly practical synthesis of tetrahydrofurofurane lignans
A new route to tetrahydrofurofurane lignans 8 is present, which starts with substituted benzoate following a 7 step syntheses, and is distinctly shorter, more economic and efficient than any of the previous approaches to the target reported in the literature. The key step to establish the first furane ring 2 benefits the remarkable ease of the Diels-Alder reaction of 2,4-diaryloxazole 1 with 2-butyne-1,4-diol diacetate.
Chen, Bingzi,Ye, Xiulin,Chen, Qingqi
p. 2831 - 2841
(2007/10/03)

An alternative diastereospecific approach to (±)-samin and 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane [furanofuran] lignans based on the Ireland-Claisen rearrangement of unsaturated oxa-macrolides
Ireland-Claisen rearrangement of the nine-membered macrolide 22 leads stereospecifically to the tetrahydrofurancarboxylate 23, via the boat-like transition state 9. The hydroxy-acid precursor 21c to the macrolide 22 has been prepared by Michael addition of the sodium alkoxide of (Z)-allylic alcohol 20 to methyl acrylate in the presence of dimethyl sulfoxide. Subsequent conversion into the corresponding aldehyde 29, Grignard addition, cleavage of the alkene and acid-catalysed cyclisation gives (±)-sesamin 32. The epimeric ester 33 has been converted into (±)-samin 37 by related functional group manipulations, but excluding the Grignard coupling, and a final isomerisation.
Hull, Hilary M.,Jones, Richard G.,Knight, David W.
p. 1779 - 1787
(2007/10/03)

Reactions of lignan precursors, cinnamyl alcohols and cinnamic acids, with Weitz' aminium salt
Reaction of a lignans precursor, cinnamyl alcohol (2a), with Weitz' aminium salt, tris(4-bromopheny)aminium hexachloroantimonate, in THF gave cinnamaldehyde (4), a coupling product (5), and a furofuran lignan, (±)- sesamin (6). Similar reactions using related precursors 2b, 3a, 3b gave 7, 8a, 9a, 10a, 11a, and 11b.
Takeya,Ara,Tobinaga
p. 1970 - 1976
(2007/10/03)

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
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).
Suginome,Orito,Yorita,Ishikawa,Shimoyama,Sasaki
p. 3052 - 3064
(2007/10/02)

Diastereodivergent Chiral Synthesis of the Furofuran Lignans (+)-Sesamin and (-)-Asarinin
Two diastereomeric lignans (+)-sesamin and (-)-asarinin have been prepared diastereodivergently via the common intermediate generated by the chirotopical Heck reaction.
Samizu, Kiyohiro,Ogasawara, Kunio
p. 543 - 544
(2007/10/03)

A New Synthetic Route to Furofuranoid Lignans via Intramolecular Mukaiyama reaction
The sequence set out in Scheme 1 provides a short and expedient synthesis of a number of (+/-)-furofuranoid lignans, including styraxin 3 (antitumor), aptosimon 5, asarinin 6, pluviatilol 7, 'MEL' 4 (inhibitor of germination) and related compounds.
Stevens, David R.,Till, Clive P.,Whiting, Donald A.
p. 185 - 190
(2007/10/02)

A new stereo- and regioselective synthesis of (±)-sesamin involving a β-scission of alkoxyl radicals as the key step1
A new stereo- and regioselective synthesis of (±)-sesamin (a representative lignan) based on our general method for the transformation of a cyclopentanone ring into a tetrahydrofuran ring involving a regioselective β-scission of the alkoxyl radicals is reported.
Orito, Kazuhiko,Yorita, Kaoru,Suginome, Hiroshi
p. 5999 - 6002
(2007/10/02)

Enantio-controlled route to the furofuran lignans: the total synthesis of (-)-sesamolin, (-)-sesamin, and (-)-acuminatolide
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Takano,Ohkawa,Tamori,Satoh,Ogasawara
p. 189 - 191
(2007/10/02)

Synthetic methods for (Exo,Exo)- and (Exo-,Endo)-2,6-diarylbicyclo[3:3:0]octane lignans: Syntheses of (±)-aptosimon, (±)-styraxin, (±)-asarinin, and (±)-pluviatilol
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Stevens,Whiting
p. 4629 - 4632
(2007/10/02)

Synthesis and N.m.r. Spectra of 2,6- and 2,4-Diaryl-3,7-dioxabicyclooctanes
A series of isomeric 2,6- and 2,4-diaryl-3,7-dioxabicyclooctanes have been prepared via the corresponding threo, and erythro-dioxo-diesters.Comparison of their 1H and 13C n.m.r. spectra reveals small differences in chemical shifts and coupling constants which could be diagnostic in assigning structures to such compounds.The structure of 4-hydroxysesamin has been confirmed by direct correlation with sesamin.
Pelter, Andrew,Ward, Robert S.,Watson, Derrick J.,Jack, Ibiba R.
p. 183 - 190
(2007/10/02)