Anthraquinone, 2-hydroxymethyl

The methyl substituent of 2-methyl-4,8-dihydrobenzo[l,2- 5,4-. ]dithiophene-4,8-dione 118 undergoes a number of synthetic transformations (Scheme 8), and is therefore a key intermediate for the preparation of a range of anthraquinone derivatives <1999BMC1025>. Thus, oxidation of 118 with chromium trioxide in acetic anhydride at low temperatures affords the diacetate intermediate 119 which is hydrolyzed with dilute sulfuric acid to yield the aldehyde 120. Direct oxidation of 118 to the carboxylic acid 121 proceeded in very low yield however, it can be produced efficiently by oxidation of aldehyde 120 using silver nitrate in dioxane. Reduction of aldehyde 120 with sodium borohydride in methanol gives a 90% yield of 2-hydroxymethyl derivative 122 which reacts with acetyl chloride or thionyl chloride to produce the 2-acetoxymethyl- and 2-chloromethyl-4,8-dihydrobenzo[l,2-A5,4-3 ]-dithiophene-4,8-diones 123 and 124, respectively. 

Hydroxymethylation of anthraquinones (Marschalk reaction). Krohn1 has reviewed this reaction, particularly for the synthesis of anthracyclinones. It is particularly useful for preparation of optically active rhodomycinones by use of chiral aldehydes (166 references). 

Aloe-emodin (= 1,8-Dihvdroxy-3-(hydroxymethyl )-9,1 Clan thracenedione Rhabarberone) (anthraquinone)... 

Ethidium bromide (= 2,7-Diamino- 10-ethyl-9-phenyl-phenanthridinium bromide)] (phenanthridinium) [Heliquinomycin] (glycosylated rubromvcin) [4 -Hydroxymethyl-4,5, 8-trimethylpsoralen =HMT] (furanocoumarin) [Mitoxantrone] [anthraquinone]... 

Two high-yield three-step syntheses of (195) from anthraquinone have been developed via the bis-epoxide (194) (67% and 89% overall). Compound (195) was obtained from (194) either by conversion into lO-hydroxymethyl-9-anthraldehyde with LiBr, followed by oxidation, or by conversion into 9,10-dihydroanthracene-9,10-dicarboxaldehyde with BF3, followed by dehydrogenation. 

CARBOXYLIC GROUPS Chloromethyl methyl sulfide. 2-Hydroxymethyl-anthraquinone. p-Nitrobenzyl bromide. 

Protection and Deprotection.— The formation of esters of 2-hydroxymethyl-anthraquinone has been shown to be a useful method for the protection of carboxy-groups of a-amino-acids. Such derivatives, designated Maq esters, are stable to TEA, HCl, and triethylamine, and can be hydrolysed in quantitative yield by a number of methods. They offer, moreover, the advantages of high crystallinity and... 

Dihydroxy-5,8-bis ((2-hydroxyethyl) amino)-9,10-anthracenedione 1,4-Dihydroxy-5,8-bis ((2-hydroxyethyl) amino) anthraquinone 5,8-Dihydroxy-1,4-bis ((2-hydroxyethyl) amino) anthraquinone. See Disperse blue 7 (4,5-Dihydroxy-1,3-bis (hydroxymethyl)-2-imidazolidinone. See Dimethyloldihydroxyethyleneurea... 

Intact plants and cell cultures of Streptocarpus dunnii (Gesneriaceae) contain several 1,2-naphthoquinones with a reversed prenyl side chain, such as that in dunnione (66) (Fig. 6.16), l-Hydroxy-2-methylanthraquinone (67) and 1-hydroxy-2-(hydroxymethyl)anthraquinone (68) were also isolated from this culture. Administration of [1-carboxy- C]<9-succinylbenzoate revealed that was incorporated into the 1-position of dunnione and the 10-position of anthraquinones. These results, together with those of feeding experiments in which lawsone (41) and its 2-prenyl ether (69) were applied, suggested that dunnione (66) was formed by a Claisen-type rearrangement at the 2-position of 2-carboxy-4-oxotetralone (COT) (43), whereas anthraquinones were formed by prenylation at the 2-position of 2-carboxy-4-oxo-tetralone (COT) (43) or l,4-dihydroxy-2-naphthoic acid (40) (Inouye and Leistner, 1988). 

Several types of woods that contain anthraquinones and related compounds are highly resistant to attack by marine borers (Southwell and Bultman, 1971). 2-Methyl- (57), 2-hydroxymethyl- (75) and 2-formylanthraquinones in the heartwood of teak (Tectona grandis, Verbenaceae) are effec-... 

Anthraquinones yellow, orange, red, red-brown or violet derivatives of anthraquinone (9,10-anthrace-nedione), the largest group of naturally occurring qui-nones With a few exceptions, e.g. 2-methylanthraqui-none, all natural A. are hydroxylated. Other common substituents are methyl, hydroxymethyl, methoxy, formyl, carboxyl, benzyl and long-chain alkyl groups. Some A., are dimeric. 

Prenyl-naphthohydroquinone-2-carboxyhc acid is the key intermediate in the formation of anthraquinones of the alizarin type. (In contrast the A-ring-substituted anthraquinone derivatives found in fungi and certain higher plants, e.g., Rhamnaceae and Polygonaceae, are polyketides, D 3.3.5). In the biosynthesis of alizarin one C-atom of the isoprene residue is lost. In structurally related compounds, however, this C-atom may still be present in the form of a methyl, hydroxymethyl, aldehyde, or carboxy group. 

A very important group of polyhydroxysubstituted anthraquinones substituted at both aromatic rings are emodins (9-160). A common feature of these anthraquinones is the presence of at least two OH groups (at C-1 and C-8) and a methyl group (at C-3) or its oxidised forms (hydroxymethyl or carboxyl group). 

Aloin ( barbaloin ) is an anthraquinone component found in the latex of various species of aloe used to prepare the pigment known as aloe brown. The molecule, 10-glucopyranosyl-l, 8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone, is built from aloe-emodin q.v. Merck Index, 1996)... 

Itokawa et al 74) reported the NMR spectra of some anthraquinones isolated from Rubia species. For one of the compounds a 2-methyl-1,3,6 (or 7)-trihydroxy-9,10-anthraquinone structure was assumed based on various spectral data. Eventually it was stated that the hydroxyl group was in the 6-position rather than in the 7-position because of a 0.6-0.8 ppm upfield shift observed for C-9 if compared with compounds having a 1,3-dihydroxy-2-hydroxymethyl substitution pattern. For a better insight in the validity of using NMR spectrometry for distinguishing 6/7 or 2/3 substitution in anthraquinones bearing several substituents, further NMR studies of such multiply-substituted anthraquinones seem desirable. 

Incorporation of an anthraquinone moiety, attached through an acyclic backbone unit, into a duplex DNA such that the anthraquinone was opposed to 5-methyl-dC resulted in an efficient one-electron oxidation to 5-formyl-dC or 5-hydroxymethyl-dC. Treatment of the duplex with hot piperidine led to strand-specific cleavage at the oxidised cytosine base. An anthraquinone has been used to link chimeric a-p oligonucleotides for formation of alternate-stranded triplexes. The two oligonucleotides were linked through a substituted propionic acid derivative which was further conjugated to the anthraquinone via various polyamines. 

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