4- Hydroxy-l-methyl-2-quinolone

Confirmation of the isoprenoid nature of the furan rings of dictamnine (328) and of N-methylplatydesminium salt (326) in S. japonica was provided indirectly by Grundon and his co-workers (224), who showed that the 3-prenylquinolones 321 and 322 labeled at - with 14C were good precursors of both alkaloids (3.6-4.8% incorporation). Specific incorporation of the precursors into dictamnine was indicated by oxidative degradation by a method similar to that used previously. N-Methylplatydesminium salt was counted as its base-cleavage product edulinine (256), which was converted into isodictamnine (Section IV,B,3) oxidation via 3-carboxy-4-hydroxy-l-methyl-2-quinolone gave 14C-labeIed carbon dioxide. 

A group of derivatives of 4-hydroxy-l-methyl-2-quinolone (57) (yields 45-80%) were synthesized by the reaction of the anhydrides 2 and 58 with the products from treatment of the carboxylic esters 59 with lithium diisopropylamide (THF, from -70 to -50°C, 1-1.5 h) [35, 36],... 

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. 

These elegant syntheses starting from the 3-methyl-2-butenal, and reaction with 4-hydroxy-2(l//)-quinolone 97a and 4-hydroxy-l-methyl-2(l//)-quinolone 97b in water at 80 C for 6h gave flindersine 98a and V-methylflindersine 98b in 70% and 64% yields, with 97c and 97d gave haplamine 98c and V-methylhaplamine 98d in 62% and 69% yields, respectively. Similarly, treatment of 97a-97d with citral in water produced cycloadducts zanthosimuline 99b and its derivatives 99a, 99c, and 99d in 62%, 71%, 64%, and 65% yields, respectively. 

Hydroxy-l-methyl-3-prenyl-2-quinolones, cf. (22), are key intermediates in the synthesis of quinoline alkaloids, and usually are prepared in one stage from an N-methyl-aniline and diethyl prenylmalonate. Interesting new methods beginning with N-methylisatoic anhydrides, cf. (20), have been explored and briefly repor-... 

C. G. Pozzi, A. C. Fantoni, A. E. Goeta, C. C. Wilson, J. C. Autino, G. Punte. Close shell interactions in 3-ethoxycarbonyl-4-hydroxy-6-methoxymethyleneoxy-l-methyl-2-quinolone 100 K single crystal neutron diffraction study and ab initio calculations. J. Mol. Struct. 753, 173-181 (2005). 

Hydroxy-l-methyl-2-phenyl-4-quinolone was obtained as a minor constituent (136). 

Hydroxy-l-methyl-2-phenyl-4-quinolone (3), obtained previously from Lunasia quercifolia, now has been isolated from Skimmia japonica. Details have been published of the Italian synthesis of halfordamine (6) (see Vol. 4 and Vol. 5 of these Reports) and related 2-quinolones. ... 

Hydroxy-l-methyl-3-phenyl-2-quinolone (56) is formed with a yield of 80% as a result of the reaction of the anhydride 2 with ethyl phenylacetate in the presence of potassium bis(trimethylsilyl)amide at -78°C [34],... 

A method was developed for the synthesis of quinoline derivatives from isatoic anhydrides and lactones. The amino ketones formed at the first stage were then converted into the desired products by cyclocondensation after isolation or by direct heating of the reaction mass. Thus, the reaction of the anhydride 2 with the butyrolactones 94 in the presence of lithium diisopropylamide gave the amino ketones (95) (yield 99%), which when boiled in toluene gave 4-hydroxy-3-R-l-methyl-2-quinolones 96 (yield 98% with R = H or 70% with R = Me). It was established that the latter exist in two isomeric forms 96a,b [57],... 

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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