- Experiments Directed Towards the Synthesis of Anthracyclinones. XXVI. The Preparation of Chiral Intermediates for Anthracyclinone Synthesis
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(2'R)-1,5-Dimethoxy-2-(2'-methyloxiran-2'-ylmethyl)anthraquinone (8), an intermediate for the synthesis of fridamycin E, has been prepared enantioselectively via the diol (15).The diol (15) was prepared in high yield by asymmetric cis-hydroxylation of the alkene (11).The analogous diol (22), a vineomycinone B2 precursor, was also prepared.
- Beauregard, Daniel A.,Cambie, Richard C.,Dansted, Paul C.,Rutledge, Peter S.,Woodgate, Paul D.
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- APPROACHES TO THE REGIOSPECIFIC SYNTHESIS OF ANTHRACYCLINE ANTIBIOTICS
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Synthetic approaches to anthracycline antibiotics were studied through the use of Claisen rearrangements on 1-methallyloxy-5-methoxyanthraquinone (9) which required reducing conditions to proceed through a hydroquinone intermediate in situ. 1-(2'-Methylene-4'-pentenoxy)-5-methoxyanthraquinone (13) underwent a similar reductive rearrangement but also produced a spiro compound 16 as a result of an ene reaction between the phenol and side chain double bond. 1-Hydroxy-2-methallyl-5-methoxyanthraquinone (11) could not be oxidized to quinizarin 17. 1-Hydroxy-2-methallyl-5,9,10-trimethoxyanthracene (21) was oxidatively coupled to the dimer at C-2.Dimer 23 reacted with diazomethane to form a 1,3-dipolar adduct 24.
- Baldwin, Jack E.,Rajeckas, Algis J.
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- A General, Regiospecific Synthesis of Highly Substituted Quinones
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A general route to a wide variety of substituted quinones (furyl, indolo, pyrrolo, quinolino, naphtho, and anthra) has been developed via the thermolysis (160 deg C, xylene) and subsequent oxidation (air or Ce4+) of 4-hydroxy-4-substituted-cyclobutenones (eq. 1) and 2-hydroxy-2-substituted-benzocyclobutenones which were formed by the regioselective addition of an appropriate aryl or heteroaryl (etc.) lithium reagent to the correspnding cyclobutenedione.
- Liebeskind, Lanny S.,Iyer, Suresh,Jewell, Charles F.
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p. 3065 - 3067
(2007/10/02)
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- Selective Dealkylation of Methoxyanthraquinones via Difluoro1,O9>boron Chelates: Synthesis of Hydroxymethoxyanthraquinones
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1,8-, 1,5- 1,2-, and 1,4-Dimethoxyanthraquinones have been treated with boron trifluoride-diethyl ether to give difluoro(anthraquinonato)boron chelates (1a-d) respectively. 1,4,5-Trimethoxyanthraquinone was similarly converted separately in benzene and toluene into the mono- (2) and bis-difluoroboron(3)-chelates respectively, and 2,2',4,4'-tetramethoxybenzophenone was converted by BF3*Et2O in toluene into the boron adduct (4).Treatment of these derivatives, (1a-d) and (2)-(4), with methanol gave the following uncomplexed derivatives in good yield respectively: 1-hydroxy-8-methoxyanthraquinone, 1-hydroxy-5-methoxyanthraquinone, 1-hydroxy-2-methoxyanthraquinone, 1-hydroxy-4-methoxyanthraquinone, 4-hydroxy-1,5-dimethoxyanthraquinone, 1,4-dihydroxy-5-methoxyanthraquinone, and 2-hydroxy-2',4,4'-trimethoxybenzophenone.
- Preston, Peter N.,Winwick, Thomas,Morley, John O.
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p. 1439 - 1441
(2007/10/02)
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- Selective Demethylation of Di- and Tri-methoxyanthraquinones via Aryloxydifluoroboron Chelates. Synthesis of 4-Hydroxy-1,5-dimethoxyanthraquinone and 1,4-Dihydroxy-5-methoxyanthraquinone
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Methoxyanthraquinone derivatives react with boron trifluoride-diethyl ether to give mono- and bis-difluoroboron chelates which, in methanol, are converted into hydroxyanthraquinones; an extension of this method is described for the synthesis of 2-hydroxy-2',4,4'-trimethoxybenzophenone.
- Preston, Peter N.,Winwick, Thomas,Morley, John O.
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- Anthraquinone dyestuffs
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Compounds of formula SPC1 Wherein R1 and R2 independently of one another denote optionally substituted alkyl radicals with 1-3 C atoms and R3 represents hydrogen or an optionally substituted alkyl radical with 1-5 C atoms, as well as compounds of the formula SPC2 Wherein R4 represents an alkyl group which is optionally substituted by hydroxyl or alkoxy groups, and R5 and R6 represent hydrogen or an amino group which is monosubstituted or disubstituted by a straight-chain alkyl group or a cycloalkyl group, with the proviso that R5 and R6 do not simultaneously represent hydrogen, and processes for their production.
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