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Preparation of 3,4-Dihydroanthracen-1(2H)-ones. A Synthetic Approach to Islandicin and Digitopurpone via Difluoro1,O9>boron Chelates

DOI: 10.1039/P19830000001

Source and publish data:

Journal of the Chemical Society. Perkin transactions I p. 1001 - 1007 (1983)

Update date:2022-08-30

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Authors:

Preston, Peter N.Preston, Peter N.

Will, Stephen G.Will, Stephen G.

Winwick ThomasWinwick Thomas

Morley, John O.Morley, John O.

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Article abstract of DOI:10.1039/P19830000001

Three 9,10-dihydroxyanthracen-1(2H)-one derivatives (2a-c) have been obtained by the catalytic hydrogenation of quinizarin, 1-hydroxy-5-methoxyanthraquinone, and 1-hydroxy-8-methoxyanthraquinone, respectively; in the last two reactions, monohydroxyanthracen-1(2H)-ones (4a) and (4b) are formed as by-products.The anthracenone derivatives (2a-c) were O-methylated by methyl toluene-p-sulphonate and the selective demethylation of the dimethoxy derivative (2d) to the monomethoxy derivative (2e) was effected by AlCl3.The silyl enolate (5) was unreactive toward C-methylation but the lithium enolate of the anthracenone (2d) reacted with methyl iodide to give a mixture of C-mono (2f) and C-di (6a) alkylated derivatives; in contrast, the boron enolate of (2d) reacted with methyl iodide to give exclusively the C-monomethylated derivative (2f) and this procedure was extended to the synthesis of 5-methoxy (2g) and 8-methoxy (2h) analogues of (2f).Whereas the dimethoxyanthracenone derivative (2d) is brominated (Br2-CHCl3, 0 deg C) in separate reactions to give monobromo (2i) and dibromo (6b) derivatives, the difluoroboron chelate (9a) was converted by photochemical bromination into a product (9g) of benzylic substitution; the analogue (9h) was similarly obtained from the difluoroboron chelate (9b).The boron derivatives (9g) and (9h) were transformed by methanol into hydroxydimethoxyanthracenone derivatives (2l) and (2m), and (9g) was also converted by wet alumina into the dihydroxymethoxyanthracenone (2n).The hydroxydimethoxyanthracenone (2l) and (2m) were transformed by 2,3-dichloro-5,6-dicyanobenzoquinone and selenium dioxide into 1-hydroxy-4-methoxyanthraquinone and 1-hydroxy-4-methoxy-2-methylanthraquinone, respectively.

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Product name:1-Hydroxy anthraquinone

Cas No:129-43-1

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