title: Bidirectional racemic synthesis of the biologically active quinone cardinalin 3.
abstract: Readily available 2,2',6,6'-tetramethoxy-1,1'-biphenyl was transformed in 14 synthetic steps into the natural product cardinalin 3 using a bidirectional approach. One of the key steps was the formation of the cis-1,3-dimethylnaphtho[2,3-c]pyran ring. (+/-)-1,1'-[6,6'-Diallyl-5,5'-bis(benzyloxy)-1,1',3,3'-tetramethoxy-2,2'-binaphthalene-7,7'-diyl]diethanol was treated with O(2) in the presence of CuCl(2) and catalytic PdCl(2) to afford 5,5'-bis(benzyloxy)-7,7',9,9'-tetramethoxy-1,1',3,3'-tetramethyl-1H,1'H-8,8'-bibenzo[g]isochromene. Hydrogenation of this compound afforded 7,7',9,9'-tetramethoxy-cis-1,3-cis-1',3'-tetramethyl-3,3',4,4'-tetrahydro-1H,1'H-8,8'-bibenzo[g]isochromene-5,5'-diol in quantitative yield, which was converted in 3 steps to cardinalin 3.
authors.affiliation: Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, South Africa.
authors.forename: Sameshnee
authors.initials: S
authors.lastname: Govender
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Mmutlane
authors.forename: Willem A L
authors.initials: WA
authors.lastname: van Otterlo
authors.forename: Charles B
authors.initials: CB
authors.lastname: de Koning
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D016227:Benzoquinones / Q000138:chemical synthesis* / Q000737:chemistry; D007536:Isomerism; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry; D011724:Pyridazines / Q000737:chemistry; D011809:Quinones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000596:Amino Acids; D016227:Benzoquinones; D010456:Peptides, Cyclic; D011724:Pyridazines; D011809:Quinones; C523641:cardinalin 3; C414086:chloptosin