4- Hydroxy-8-methoxy-2-quinolone

In the realm of synthesis the earlier biogenetically-pattemed work of the Irish school is brought to attention. Some new syntheses follow conventional lines, while an attempt to use a diazomethane homologation reaction on 3-isobutyryl-4-hydroxy-8-methoxy-2-quinolone to produce lunacrine alkaloids was largely unsuccessful. Two neat oxidative interconversions of furoquinoline alkaloids have been reported. ... 

Japonine (16), the 3-methoxy-4-quinolone of Orixa japonica (see Vol. 2), has beeen synthesized21 (Scheme 2). The key compound (15 R = OMe) was prepared in good yield by the method used to make the analogous 3-hydroxy-4-quinolone (15 R = H) methylation with methyl iodide and potassium hydroxide in DMF then afforded japonine as the major product. 

For the preparation of 4-(1.2.3.4-tetrahydroquinolino)-phenol 17 three different procedures were worked out [Eqs. (6)-(8)]. 17 was prepared by reacting N-p-methoxyphenyl-anthranilic acid with acetic anhydride and subsequent saponification to l-p-methoxyphenyl-4-hydroxy-2-quinolone, reaction withPOCl3 to form l-p-methoxyphenyl-4-chloro-2-quinolone, hydrogenation to l-(p-methoxy-phenyl)-3.4-dihydro-2-quinolone, splitting the ether with HBr to l-(p-hydroxy-phenyl)3.4-dihydro-2-quinolone, and reduction with LiAlH4 [Eq. (6)J. Another synthetic possibility was the reaction of p-anilinophenol with (3-propiolactone and subsequent cyclization to l-(p-acetoxyphenyl)2.3-dihydro-4-quinolone 18. The next step, the Wolff-Kishner reduction, led directly to the desired product [Eq. (7)]. The third way, the direct amination of p-iodoanisole with 1.2.3.4-tetrahydro-quinoline and the subsequent splitting of 4-(1.2.3.4-tetrahydro-quinolino)-anisol with HBr was the best one [Eq. (8)]. Saponification of l-(p-acetoxyphenyl>2.3-... 

Hydroxy-2-quinolone is a biosynthetic precursor of quinoline alkaloids (see Section VII), and it is not surprising that compounds of this type occur in rutaceous plants (Volume IX, p. 225). Additional 4-methoxy-2-quinolones with or without N-methyl groups have now been reported. 

Methoxy-l-methyl-2-quinolone (1) was isolated from Hesperethusa crenulata M. Roem. (12) and from the wood of Fagara boninensis (13). The alkaloid folimine from Haplophyllum foliosum Vved. (14) was identified as 4,8-dimethoxy-l-methyl-2-quinolone (2), which had been obtained earlier during the degradation of foliosine (Volume IX, p. 225). Folifidine from H. dubium Eug. Kor (15) and from H. foliosum (16) is the 8-hydroxy-2-quinolone 3. 

Huffman and Hsu (93) prepared flindersine and its 8-methoxy derivative from thallous salts of 4-hydroxy-2-quinolones and 3-chloro-3-methylprop-... 

Cell suspension cultures of R. graveolens grown in the presence of 4-hydroxy-2-quinolone show increased amounts of quinoline and furoquinoline alkaloid production. For example, the concentration of dictamnine increased as long as 4-hydroxy-2-quinolone was present in the culture medium as soon as the quinolone was depleted, rapid transformation of dictamnine into 8-methoxy-dictamnine was observed. ... 

Recently kinetic data have become available for the nitration in sulphuric acid of some of these hydroxy compounds (table 10.3). For 4-hydroxyquinoline and 4-methoxyquinoline the results verify the early conclusions regarding the nature of the substrate being nitrated in sulphuric acid. Plots of log Q against — (Lf + logioflHao) fo " these compounds and for i-methyl-4-quinolone have slopes of i-o, i-o and 0-97 at 25 C respectively, in accord with nitration via the majority species ( 8.2) which is in each case the corresponding cation of the type (iv). At a given acidity the similarity of the observed second-order rate constants for the nitrations of the quinolones and 4-methoxy-quinoline at 25 °C supports the view that similarly constructed cations are involved. Application of the encounter criterion eliminates the possibilities of a... 

Methoxy-2-phenylquinoline, 5-hydroxy- l-niethyl-2-phenyl-4-quinolone. (-)-O-methylluninium salts, lunasine, 4-me[hoxy-2-(3, 4>methylenedioxyphenyl)quinoline, eduline, lunatnarine, limine, hydroxylunine, lunucrine, hydroxylunacrine, hydroxylunidine, lunacridine, hydroxylunacridine, lunacrinol... 

The prenylquinoline derivatives (142), (143), and (147) and 4-hydroxy- and 4-methoxy-2-quinolone are good precursors for dictamnine. Incorporation of... 

A soln. of 4-hydroxy-8-methoxy-l-methyl-3-(3-methylbut-2-enyl)-2-quinolone in lerf-butanol containing coned. H2SO4 treated with excess peroxylauric acid and stored 3 days at 18° ( ) -balfourodine. Y 95%. E. A. Clarke and M. F. Grundon,... 

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