L-Methyl-2-quinolone

The aposematic beetle, Metriorrhynchus rhipidius, contains three pyrazines as warning odor components and two amides as bitter principles (Tables III, V, and VIII) (97). Of the three components with the beetlelike odor, the most characteristic is 2-methoxy-3-isopropylpyrazine (24b). The other two components are 2-methoxy-3-methylpyrazine (24a) and 2-methoxy-3-sec-butylpyrazine (24d). It would seem likely that these compounds will occur in the defensive systems of the aposematic beetles. The two amide components, detectable in the hemo-lymph exuded by adult beetles, are 3-phenylpropanamide (130) and l-methyl-2-quinolone (57), the latter being the major component. It seems likely that these bitter principles contribute to distastefulness to potential predators. 

The structure of l-methyl-2-quinolone (57), from the aposematic beetle in the genus Metriorrhynchus (Table V), was expected from the mass spectral data and was confirmed by comparison with an authentic sample (97). 

Phenylpropanamide (130), from the aposematic beetle (genus Metrior-rhynchus) (Table VIII), has been purified by gas chromatography from the methanol extract. Its structure is presumed from mass spectral data and was confirmed by comparison with a synthetic sample (97). The co-occurrence of amide 130 and l-methyl-2-quinolone (57) in this beetle suggests a common pathway of biosynthesis and that they may be derived from the amino acid phenylalanine. 

A new approach to the synthesis of 4-alkoxy-l-methyl-2-quinolones has been described (Scheme 3).18 Irradiation of 4-alkoxy-2-methylquinoline 1-oxides (12) (prepared from 2-methyl-4-nitroquinoline 1-oxide) results in photo-rearrangement to give the 2-quinolones (13) as major products a mechanism (Scheme 3) has been proposed. The alkaloids (13 R = Me) and ravenine (13 R = CH2CH=CMe2), which have been synthesized by other means, were prepared in this way. 

The wood of this plant yielded, among other and neutral products, 4-methoxy-l-methyl-2-quinolone (mp 99-103°). The bark yielded nitidine, aricine, chelerythrine, isolated as derivatives, and oxynitidine (mp 283-285°). In addition l-( + )-armepavine metho salt was also found (171). 

Haplopine (1 R1 = H, R2 = OH, R3 = OMe) 4-Methoxy- l-methyl-2-quinolone Robustine Skimmianine... 

Non-hemiterpenoid Quinolines.—New sources of the simple quinolines 4-methoxy-l-methyl-2-quinolone and its 8-methoxy-derivative (folimine) have been reported the former was isolated from Myrtopsis sellingii9 and from Zanthoxylum cuspidatum,16 and folimine was shown to be a constituent of Haplophyllum perforatum.5 The latter species also contains foliosidine (9), previously isolated from H. foliosum. The micro-organism Pseudomonas aertiginosa has been shown to contain 2-(hept-l-enyl)-4-quinolone (12).10 The structure of the alkaloid was established by n.m.r. and mass spectroscopy and by its synthesis from aniline and the j3-keto-ester Me(CH2)4CH=CHC0CH2C02Me. 

The UV-spectrum of lunacridine, which is unchanged in acid or alkali, is consistent with the presence of a 2-quinolone system the batho-chromic shift of the maxima at 284 and 294 m/x, in comparison with those of 4-methoxy-l-methyl-2-quinolone (268 and 278 m/a), can be attributed... 

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). 

Cook (44) has prepared a number of crystalline basic salts of various organic bases with acids such as HAsFj. From their infrared spectra he predicted that many of them should have Type A structures of the sort described in this section. So far only two structures have been successfully elucidated. One is of an arsenate ester (45), the other of a basic salt B2. HAsFj, with S = l-methyl-2-quinolone (15), which does indeed... 

Methoxy-l-methyl-2-quinolone was isolated from the stem bark 132). 

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. 

Another 4-methoxy-l-methyl-2-quinolone (10) was isolated from the roots of Spathelia sorbifolia L. (25). The constitution of the alkaloid was established by spectroscopy and confirmed by dimethylation of quinolone 9 with dimethyl sulfate in dimethylformamide. 

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],... 

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],... 

The water insoluble bases, together with those recovered from the mother liquors of the l-methyl-2-quinolone hydrochloride, are heated with 40 cc. of fuming hydrochloric add in a sealed tube at 175 for 2.5 hours, whweby the 4-methoxy-2-n-amyl-... 

Whereas l-methyl-2-quinolones (238) do not undergo Michael addition of cyanides (KCN or Me3SiCN) due to the aromatic nature of the heterocycle, their 8-substituted... 

Iridium complex-catalyzed cyclization of an Af-arylcarbamoyl chloride with an alkyne has been reported by Tsuji and coworkers [153]. In a typical example, Af-methyl-Af-phenylcarbamoyl was reacted with 5-decyne and a catalytic amount of [IrCl(cod)]2 (2.5mol%) and additional cod (30mol%) in refluxing o-xylene for 20 h to give 3,4-dimethyl-l-methyl-2-quinolone in 92% yield (Scheme 11.5). During this reaction, no indole product formed by decarbonylation was observed. This reaction is proposed to proceed by oxidative addition of Af-arylcarbamoyl chloride to Ir(I), giving a carbamoyl chloroiridium(III) species. Subsequently, the formation of a five-membered iridacycle by ortho-aryl C-H activation followed by insertion of the alkene and reductive elimination produces the 2-quinolone derivative. 

Triethyloxonium fluoroborate added with stirring under anhydrous conditions to a soln. of l-methyl-2-quinolone in methylene chloride, stirring continued for 1 hr. l-methyl-2-ethoxyquinolinium fluoroborate (Y 96%) added during 5 hrs. under anhydrous conditions to an ice-cooled soln. of Na in ethanol 1-methyl-2-quinolone diethyl acetal (Y 87%) dissolved in ethanol, treated with cyclopentadiene, and refluxed 10min.-> (1-methyl-1,2-dihydro-2-quinolylidene)-cyclopentadiene. (Y 94%).—Amide acetals react easily without catalyst with nucleophiles, e. g. giving enamines with active methyl and methylene groups. F. e., also aliphatic amide acetals and urea acetals, as well as their reactions, s. H. Meerwein et al., A. 641, 1 (1961). 

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