- Palladium-Catalyzed Carbonylative Lactonization of Propargyl Alcohols with Organic Dichalcogenides and Carbon Monoxide
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The reaction of propargylic alcohols with diaryl disulfides and carbon monoxide in the presence of tetrakis(triphenylphosphine)palladium leads to a novel thiolative lactonization to afford β-(arylthio)-α,β,-unsaturated lactones in moderate to good yields.
- Ogawa, Akiya,Kuniyasu, Hitoshi,Sonoda, Noboru,Hirao, Toshikazu
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p. 8361 - 8365
(2007/10/03)
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- Preparation and palladium-catalysed cross-coupling reactions of 3-and 4-tributylstannylfuran-2(5H)-ones
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Stannylfuranones 1 and 2 were prepared by ipso radical desulfurative stannylation of phenylsulfanylfuranones 3 and 16. Compounds 1 and 2 underwent Stille coupling reactions with aryl iodides to give 3- and 4-arylfuran-2(5H)-ones.
- Hollingworth, Gregory J.,Perkins, Gemma,Sweeney, Joseph
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p. 1913 - 1919
(2007/10/03)
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- Synthesis of Averufin and its Role in Aflatoxin B1 Biosynthesis
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Described are two total syntheses of (+/-)-averufin (4) proceeding through a common intermediate and predicated on the efficient introduction of isotopic label(s) at side-chain and nuclear sites for the purpose of biosynthetic investigations of aflatoxin B1 (8).Using these methods, (+/-)--and --averufin, (65) and (68) respectively, and a 1:1 mixture of (+/-)-- and --averufin (71) were prepared and incorporated into aflatoxin B1 using mycelial suspensions of Aspergillus parasiticus (SU-1).In each instance efficient and specific utilization of label was observed in the product by (13)C-n.m.r.spectroscopy, demonstrating the intact incorporation of averufin.When compared with earlier observations of acetate incorporation, a complete correlation of the carbon skeleton from the intermediate anthraquinone stage of the four carbons lost in this overall process were unambiguously identified.In the formation of the dihydrobisfuran, the anthraquinone nucleus migrates to C-2' to branch the linear side-chain of averufin.Deuterium bound at C-1' in averufin is carried to C-13 of aflatoxin.Preparation from (+/-)-averufin (68) of (+/-)--averufin (73) and incorporation of the latter into versiconal acetate (5) demonstrated loss of the terminal two carbons of the averufin side-chain, presumably as acetate, by way of a Baeyer-Villiger-like oxidation.
- Townsend, Craig A.,Christensen, Siegfried B.,Davis, Steven G.
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p. 839 - 862
(2007/10/02)
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- The Regiochemistry of A-Ring-labelled Averufin Incorporation into Aflatoxin B1
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A-Ring -labelled averufin has been synthesized and found to be incorporated intact into aflatoxin B1, where the labelling pattern in the fused cyclopentenone unequivocally establishes the origin of the carbon backbone as consistent with cur
- Townsend, Craig A.,Davis, Steven G.
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p. 1420 - 1422
(2007/10/02)
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