Biomimetic studies towards the cardinalins: synthesis of (+)-ventiloquinone L and an unusual dimerisation.
Studies towards the biomimetic synthesis of cardinalin 3 are described. Despite the successful enantioselective synthesis of the monomeric pyranonaphthoquinone ventiloquinone L, it subsequently failed to undergo a proposed biomimetic homodimerisation to cardinalin 3 using a range of oxidants. However, treatment of a related naphthopyran with cerium ammonium nitrate (CAN) facilitated a tandem biaryl bond formation-oxidative demethylation sequence furnishing a dimeric pyranonaphthoquinone that had exclusively dimerised at C6. The nature of this unusual sequence is discussed and the product subsequently converted to the C6 regioisomer of cardinalin 3.
Sperry
Jonathan
J
Department of Chemistry, University of Auckland, 23 Symonds Street, Auckland. New Zealand.
Sejberg
Jimmy J P
JJ
Stiemke
Frank M
FM
Brimble
Margaret A
MA
D001572:Benzofurans / Q000737:chemistry; D016227:Benzoquinones / Q000138:chemical synthesis* / Q000737:chemistry; D001688:Biological Products / Q000138:chemical synthesis / Q000737:chemistry; D032701:Biomimetics; D019281:Dimerization; D009285:Naphthoquinones / Q000138:chemical synthesis* / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D027823:Rhamnaceae / Q000737:chemistry; D013237:Stereoisomerism
D001572:Benzofurans; D016227:Benzoquinones; D001688:Biological Products; D009285:Naphthoquinones; D011714:Pyrans; C523641:cardinalin 3; C501541:ventiloquinone L; C082022:phthalide