- First enantioselective total synthesis of altersolanol A
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The first enantioselective total synthesis of altersolanol A, a secondary metabolite from the endophytic fungi Stemphylium globuliferum and Alternaria solani, is described. The key step towards the tetrahydroanthraquinone core was an asymmetric Diels-Alder (D-A) cycloaddition promoted by (R)-3,3′-diphenyl-BINOL/boron Lewis acid with good to excellent yields and excellent diastereo- and enantioselectivity (>95 : 5 dr and 98 : 2 er).
- Mechsner, Bastian,Hen?en, Birgit,Pietruszka, J?rg
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p. 7674 - 7681
(2018/11/02)
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- Alterporriol D and E, Modified Bianthraquinones from Alternaria porri (Ellis) Ciferri
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A culture liquid of Alternaria porri afforded novel bianthraquinones named alterporriol D and E, whose structures were determined by spectroscopic methods as well as by degradation to the known compound.Alterporriol D and E were found to be atropisomers of each other.
- Suemitsu, Rikisaku,Sakurai, Yoshiaki,Nakachi, Kenji,Miyoshi, Isao,Kubota, Masakazu,Ohnishi, Keiichiro
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p. 1301 - 1304
(2007/10/02)
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- rac-Altersolanol A and Related Tetrahydroanthraquinones, Total Synthesis and Cytotoxic Properties
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A key step in the first synthesis of racemic altersolanol A (1a) is the regioselective Diels-Alder reaction of 5-acetoxy-7-methoxy-1,4-naphthoquinone (12) with 2-methyl-1-(trimethylsiloxy)-1,3-butadiene (13) to afford the adduct 14.The structure of 14 has been confirmed by X-ray measurements.The hydroxy groups of ring A are introduced by epoxidation of 14 to 20, rearrangement to the allylic alcohol 26, epoxidation to 31, and opening of the oxirane to rac-altersolanol A (1a).Similar products were obtained starting from juglone (15).Many of the intermediate epoxidesand also compounds 42-44 show remarkable cytotoxicity in cell cultures but all compounds were too toxic to be useful as anticancer agents.
- Krohn, Karsten,Markus, Helga,Kraemer, Hans Peter,Frank, Walter
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p. 1033 - 1042
(2007/10/02)
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- ALTERPORRIOL C: A MODIFIED BIANTHRAQUINONE FROM ALTERNARIA PORRI
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The spent growth medium and mycelia of Alternaria porri afforded a novel anthraquinone named alterporriol C, whose structure was determined by spectroscopic methods as well as by degradation to known compounds.Alterporriol C was found to be an α,β'-bianthraquinone derived from macrosporin and altersolanol A.Key Word Index - Alternaria porri; α,β'-bianthraquinone; alterporriol C.
- Suemitsu, Rikisaku,Ueshima, Toshibumi,Yamamoto, Toshinari,Yanagawase, Satoshi
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p. 3251 - 3254
(2007/10/02)
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