5.6- Dihydroxy-2-methyl-1,4-naphthoquinone

Animals caimot synthesize the naphthoquinone ring of vitamin K, but necessary quantities are obtained by ingestion and from manufacture by intestinal flora. In plants and bacteria, the desired naphthoquinone ring is synthesized from 2-oxoglutaric acid (12) and shikimic acid (13) (71,72). Chorismic acid (14) reacts with a putative succinic semialdehyde TPP anion to form o-succinyl benzoic acid (73,74). In a second step, ortho-succmY benzoic acid is converted to the key intermediate, l,4-dihydroxy-2-naphthoic acid. Prenylation with phytyl pyrophosphate is followed by decarboxylation and methylation to complete the biosynthesis (75). 

Further reduction of quinones - acquisition of four or more hydrogens per molecule - was achieved with lithium aluminum hydride which reduced, in yields lower than 10%, 2-methyl-1,4-naphthoquinone to 1,2,3,4-tetrahydro-l,4-dihydroxy-2-methylnaphthalene and to l,2,3,4-tetrahydro-4-hydroxy-l-keto-2-methylnaphthalene [931]. Lithium aluminum hydride [931], sodium borohydride, lithium trie thy Iborohydride and 9-borabicyclo[3.3.1Jnomine [100] converted anthraquinone to 9,10-dihydro-9,10-dihydroxyanthracene in respective yields of 67, 65, 77 and 79%. 

Menaquinone. The incorporation of [2- C]mevalonate and [2- C]-2-methyl-l,4-naphthoquinone into MK-4, normally considered a bacterial quinone, has been demonstrated in marine invertebrates such as crabs and starfish." Incorporation into 2,3-epoxy-MK-4 (163) was also observed. Cell-free extracts have been prepared from Escherichia coli which catalyse the conversion of o-succinylbenzoic acid (164) into l,4-dihydroxy-2-naphthoic acid (165) and menaquinones. In the presence of farnesyl pyrophosphate the major menaquinone produced was MK-3. Genetic studies with mutants of E. coli K12 that require (164) offer support for the generally accepted pathway for MK biosynthesis via (164) and (165)." The enzyme system that catalyses the attachment of the polyprenyl side-chain to 1,4-dihydroxy-2-naphthoic acid to form demethylmenaquinone-9 (166) has been isolated from E. colU ... 

Fusarubin. 374-Dihydro-3,6,9-trihydroxy-7-nietti-oxy-i-metbyi-1 H-nophtho 2,3-cjpyran-5,10-diune 5,8-di-h ydroxy-2-hydroxy-methyl)-6-methoxy-l, 4-naphthoquinone oxyjavanicin. C HmO, mol wt 306.26. C 58.82%, H 4.61%, O 36.57%. 1 solti from Fusarium solani Ruelius, Gauhe, Ann. 569, 38 (]950). Structure Hardegger et al. Helv. Chim. Acta 47, 2027 (1964). Efficient total synthesis Y, Tanoue ei al. Bull Chem. Soc. 60, 2927 (1987). 

Javanicin, 5,8-Dihydroxy-6-methoxy-2-methyi-3-(2-oxopropyt)-I,4-naphthalenedione 3-acetonyi-5,8-dihydr-oxy-6-methoxy-2-methyl-1,4-naphthoquinone. C,(H,4Ot ... 

A naphthoquinone dyestuff which is the principal colouring matter derived from the roots of the plant Alkanna lehmannii Tineo ( Alkanet q.vl). Chemically this is (S)-5,8-dihydroxy-2-(l-hydroxy-4-methyl-3-pentenyl)-l,4-naphthalenedione (or (1-hydroxy-3-isohexenyl)naphthazarine). It is soluble in organic solvents, but only sparingly soluble in water. The colour varies according to pH buffered aqueous solutions are red at pH 6.1, purple at pH 8.8 and blue at pH 10.0 (Merckindex, 1996, Mills and White, 1994). It is catalogued by the Colour Index as Cl 75530. 

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