- Kolbe-Schmitt type reaction under ambient conditions mediated by an organic base
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The combined use of an organic base for resorcinols realized a Kolbe-Schmitt type reaction under ambient conditions. When resorcinols (3-hydroxyphenol derivatives) were treated with DBU under a carbon dioxide atmosphere, nucleophilic addition to carbon dioxide proceeded to afford the corresponding salicylic acid derivatives in high yields.
- Sadamitsu, Yuta,Okumura, Akira,Saito, Kodai,Yamada, Tohru
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supporting information
p. 9837 - 9840
(2019/08/20)
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- Reaction of Ph3P(SCN)2 with further orthohydroxy carboxylic acid systems, including substituted β-keto acids: Synthesis of novel 2-thio-1,3-oxazines and their subsequent transformation with amines
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We now report the first reaction of Ph3P(SCN)2 with 4,6-dihydroxy-5- methylisophthalic acid to give 10-methyl-2,8-dithio-1,3-oxazino-1,3-benzoxazine- 4,6-dione. Also, the enol tautomer has been utilized in the reaction of β-keto acids with Ph3P(SCN)2 to give novel 2-thio-1,3-oxazines. Subsequent reaction of the 2-thio-1,3-oxazines with benzylamine resulted in opening of the oxazine ring and gave novel dibenzylamino-enamides, which could be cyclized to thiouracils. The reaction of 2-thio-1,3-oxazines with morpholine at low temperature led to the production of unstable 2-Mercapto-2-morpholino-1,3- oxazines. 2-Mercapto-2-morpholin-4-yl-2,3,5,6,7,8-hexahydro-4H-1,3-benzoxazin-4- one was observed to lose H2S at room temperature to give 2-morpholin-4-yl-5,6,7, 8-tetrahydro-4H-1,3-benzoxazin-4-one, which was subsequently tested and found to exhibit some antiplatelet activity. Copyright Taylor & Francis Group, LLC.
- Pritchard, Kaylene M.,Al-Rawi, Jasim
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experimental part
p. 4076 - 4096
(2009/04/11)
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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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