Concise synthesis and confirmation of the absolute configurations of naturally occurring bioactive 2,7′-cyclolignans

Nannaphat ChumsriChutima KuhakarnPawaret LeowanawatVichai ReutrakulDarunee SoorukramMahidol University2022-08-042022-08-042021-03-02Tetrahedron Letters. Vol.66, (2021)18733581004040392-s2.0-85100531346https://repository.li.mahidol.ac.th/handle/20.500.14594/76251A concise asymmetric synthesis of naturally occurring bioactive 2,7′-cyclolignans, namely 4,4′-dihydroxy-3′,5,5′-trimethoxy-2,7′-cyclolignan and 4,4′-dihydroxy-3,3′,5-trimethoxy-2,7′-cyclolignan, possessing the uncommon 8,8′-syn dimethyl stereochemistry and unsymmetrical C-6 units with 7′,8′-anti-orientation is described using a substrate-controlled stereoselective Friedel-Crafts cyclization as the key step. The products were obtained in good yields with high stereoselectivity. The absolute configurations of natural 4,4′-dihydroxy-3′,5,5′-trimethoxy-2,7′-cyclolignan and those of natural 4,4′-dihydroxy-3,3′,5-trimethoxy-2,7′-cyclolignan were assigned as (7′S,8S,8′S) and (7′R,8R,8′R), respectively, based on the experimental circular dichroism (CD) spectra of the corresponding synthesized compounds.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyChemistryPharmacology, Toxicology and PharmaceuticsConcise synthesis and confirmation of the absolute configurations of naturally occurring bioactive 2,7′-cyclolignansArticleSCOPUS10.1016/j.tetlet.2021.152827