title: Synthesis of regioisomeric analogues of crisamicin A.
abstract: The synthesis of bis-furonaphthopyrans 12a and 12b, regioisomeric analogues of the dimeric pyranonaphthoquinone antibiotic crisamicin A 1 is described. The key intermediate 16 was prepared via a one-pot in situ Suzuki-Miyaura homocoupling of naphthyl triflate 23 using bis(pinacolato)diboron. Oxidation of binaphthyl 16 to bis-naphthoquinone 14 was then effected with silver(II) oxide and nitric acid. Efficient double furofuran annulation of bis-naphthoquinone 14 with 2-trimethylsilyloxyfuran 8 afforded bis-furonaphthofuran adducts 13a and 13b as an inseparable 1:1 mixture of diastereomers. Oxidative rearrangement of this mixture of bis-furonaphthofuran adducts 13a and 13b using silver(II) oxide and nitric acid afforded unstable bis-furonaphthopyrans 12a and 12b also as a 1:1 mixture of diastereomers. Addition of 2-trimethylsilyloxyfuran 8 to naphthoquinone 25 afforded adduct 26 that underwent oxidative rearrangement to furonaphthopyran 27, however attempts to effect Suzuki-Miyaura homocoupling of triflates 26 and 27 to their respective dimers 13 and 12, was unsuccessful.
authors.affiliation: Department of Chemistry, University of Auckland, 23 Symonds St., Auckland, New Zealand.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Brimble
authors.forename: Michelle Y H
authors.initials: MY
authors.lastname: Lai
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000737:chemistry; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009285:Naphthoquinones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D009285:Naphthoquinones; C048652:crisamicin A