- A sterically encumbered photoredox catalyst enables the unified synthesis of the classical lignan family of natural products
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Herein, we detail a unified synthetic approach to the classical lignan family of natural products that hinges on divergence from a common intermediate that was strategically identified from nature's biosynthetic blueprints. Efforts toward accessing the common intermediate through a convergent and modular approach resulted in the discovery of a sterically encumbered photoredox catalyst that can selectively generate carbonyl ylides from electron-rich epoxides. These can undergo concerted [3 + 2] dipolar cycloadditions to afford tetrahydrofurans, which were advanced (2-4 steps) to at least one representative natural product or natural product scaffold within all six subtypes in classical lignans. The application of those synthetic blueprints to the synthesis of heterolignans bearing unnatural functionality was demonstrated, which establishes the potential of this strategy to accelerate structure-activity-relationship studies of these natural product frameworks and their rich biological activity.
- Alfonzo, Edwin,Beeler, Aaron B.
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p. 7746 - 7754
(2019/08/30)
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- Efficient rhodium-catalyzed conjugate addition of arylboronic acids to unsaturated furano esters for the highly stereoselective synthesis of four natural trisubstituted furanolignans
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Four natural lignans, (±)-dihydrosesamin (1a), (±)- lariciresinol methyl ether (1b, (±)-sanshodiol methyl ether (1c) and (±)-acuminatin methyl ether (1d), were prepared stereoselectively in five steps from a 4-(arylmethylene)-2-methoxy-tetrahydrofuran der
- Mondiere, Aurelie,Pousse, Guillaume,Bouyssi, Didier,Balme, Genevieve
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scheme or table
p. 4225 - 4229
(2011/02/24)
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- Reagent-controlled stereoselective synthesis of lignan-related tetrahydrofurans
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The reaction of ring-closing metathesis-derived cyclic allylsiloxanes 3 with aldehydes in the presence of a Lewis acid gives 2,3,4-trisubstituted tetrahydrofurans related to the furanolignan family of natural products. The reactions proceed with complete
- Miles, Steven M.,Marsden, Stephen P.,Leatherbarrow, Robin J.,Coates, William J.
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p. 6874 - 6882
(2007/10/03)
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- Short and stereoselective total synthesis of furano lignans (±)-dihydrosesamin, (±)-lariciresinol dimethyl ether, (±)-acuminatin methyl ether, (±)-sanshodiol methyl ether, (±)-lariciresinol, (±)-acuminatin, and (±)-lariciresinol
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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
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p. 3242 - 3248
(2007/10/03)
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- Stereoselective synthesis of trisubstituted tetrahydrofurans by radical cyclisation reaction using a hypophosphite salt. Application to the total synthesis of (±)-dihydrosesamin
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The stereoselective synthesis of tetrahydrofurans has been achieved from bromoalkynes and bromoalkenes by intramolecular radical cyclisation using a hypophosphite salt. This radical cyclisation strategy has successfully been applied to the total synthesis
- Chandra Roy, Subhas,Guin, Chandrani,Kumar Rana, Kalyan,Maiti, Gourhari
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p. 2435 - 2439
(2007/10/03)
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- Short and stereoselective total synthesis of (±)-dihydrosesamin and (±)-acuminatin methyl ether by radical cyclisation of epoxides using a transition-metal radical source
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Short, efficient and stereoselective synthesis of a furano lignans, (±)- Dihydrosesamin and (±)-Acuminatin Methyl Ether has been achieved in good overall yield through the radical cyclisation of epoxides using a Ti(III) reagent as the radical initiator.
- Rana,Guin,Roy
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p. 1249 - 1250
(2007/10/03)
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- Radical cyclisation route to furanolignans: short and stereoselective synthesis of (+/-)-dihydrosesamin and (+/-)-lariciresinol
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The furanolignans, (+/-)-dihydrosesamin 3a, and (+/-)-lariciresinol 4 have been synthesised by a very short and stereoselective route in good overall yield using a radical cyclisation as the key step.The radical precursor 2, prepared from the easily acces
- Maiti, Gourhari,Adhikari, Sankar,Roy, Subhas Chandra
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p. 927 - 930
(2007/10/02)
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- Short and stereoselective synthesis of (±)-dihydrosesamin by a radical cyclisation reaction
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A short and stereoselective synthesis of (±)-dihydrosesamin 1 has been achieved from 2 by intramolecular radical cyclisation reaction in good overall yield.
- Maiti,Adhikari,Roy
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p. 3985 - 3986
(2007/10/02)
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- Stereospecific Synthesis of the 2,3-trans-3,4-cis Trisubstituted Tetrahydrofuran Lignan(+/-)-Dihydrosesamin
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It is shown that the stereochemistry of additions to the 3-arylidene lactones 3 and 9 is controlled by the 5- rather than the 4-substituent; synthesis of the 2,3-trans-3,4-cis lignan dihydrosesamin 11b (R = H) thus requires use of the 4,5-cis- lactone 8,
- Stevens, David R.,Whiting, Donald A.
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p. 633 - 637
(2007/10/02)
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- Synthesis of the Lignan (+/-)-Dihydrosesamin: Problems of Stereocontrol in the Formation of 2,3,4-Trisubstituted Tetrahydrofurans and Tetrahydrofuranones
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It is shown that the stereochemistry of addition reactions to 3-arylidene lactones (3) and (9) is controlled by the 5- rather than the 4-substituent: synthesis of the 2,3-trans 3,4-cis lignan dihydrosesamin (11) thus requires use of the 4,5-cis lactone (8), with epimerisation at C-2 following establishment of 3,4-cis geometry.
- Stevens, David R.,Whiting, Donald A.
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p. 425 - 426
(2007/10/02)
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