67560-65-0Relevant articles and documents
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.
NOVEL BENZYLIC ETHER REDUCTIONS IN LIGNAN BIOGENESIS IN FORSYTHIA INTERMEDIA
Katayama, Takeshi,Davin, Laurence B.,Chu, Alex,Lewis, Norman G.
, p. 581 - 592 (2007/10/02)
Forsythia intermedia cell-free preparations catalyse the stepwise conversion of pinoresinol into secoisolariciresinol via lariciresinol; to our knowledge, this represents the first documented example of the reduction of benzylic ethers (or their quinone methide analogues) in plants.In this study, the specifity of the reductive steps was established: with (+)- and (-)-pinoresinols as substrates, it was found that their overall conversion into lariciresinol was highly enantioselective (i.e > 99:1 in favour of the (+)-antipode), whereas (-)-secoisolariciresinol formation was more strictly enantioselective with only reduction of (+)-lariciresinol being observed.Under the conditions examined to date, it was not possible to demonstrate the NADP-dependent back reaction using (+/-)-lariciresinols as substrates.Interestingly, neither (+)- nor (-)-epipinoresinols underwent similar reduction to afford lariciresinol, epilariciresinol or secoisolariciresinol. Key Word Index - Forsythia; Oleaceae; biosynthesi; oxidoreductase; stereoselectivity; enantiospectifity; coniferyl alchols; lignans; lariciresinol; pinoresinol; secoisolaricireinol; epipinoresinol; quinone methide.