3- Methylbenzo quinoline

The 7V-methylbenzo[( e]quinoline 426 was prepared by trapping the insertion product of an internal alkyne with a tertiary dimethylamine. One methyl group is eliminated. The dimethylaminonaphthalene-Pd complex 427 is an active catalyst and other Pd compounds are inactive[290a]. 

Nitropyrido[l,2-A]quinolin-6-ium-l 1-olate (6%) was isolated from a reaction mixture obtained by photoirradiation of crystalline photochromic 2-(2, 4 -dinitrobenzyl)pyridine for 10 days <2004JP0865>. Reaction of l-(3-chloropropyl)-6,7-dimethoxy-3-methylbenzo[c]pyrylium perchlorate with hydrazines and hydroxylamine in refluxing MeOH afforded 9,10-dimethoxy-6-methyl-, -4,6-dimethyl-l,2,3,4-tetrahydropyridazino[6,l-tf]isoquinoli-nium, and 9,10-dimethoxy-6-methyl-l,2,3,4-tetrahydro[l,2]oxazino[3,2- ]isoquinolinium, perchlorates, respectively <2004CHE1131>. 

Quinoline-3,-4-dione is an impure yellow powder (31G959) and its 2-hydroxy-7-methyl analog (or tautomer) was obtained from 7-methylquino-line-2-one by oxidation with chromic acid. With alkali it is decomposed to 4-methylbenzoic acid (48CB483). 

Although 1-aza-l,3-dienes are somewhat reluctant to undergo [4+2] cycloadditions, a,3-unsaturated l drazones show increased reactivity with electrophilic dienophiles. behaving as 1-amino-l-aza-l,3-dienes. For example, the M-dimethylhydrazone derived from methacrolein gives a high yield of 3-methylbenzo[g]quinolin-5,10-dione (62) via the adduct (61) on reaction with an excess of naphtho-1,4-quinone (B. Serckx-Poncin, A.-M. Hesbain-Frisque and L. Ghosez, Tetrahedron Letters, 1982, 3261). 

Benzocyclohexenone reacts with l-aminoprop-2-ene to give the imine (82), formally a derivative of 1-naphtltylamine, which after base induced isomerisation to the azadiene (83) undergoes a thermal electrocyclisation to the 3-methylbenzo[d,e)quinoline (84) (C.K. Govindan a d G. 

Examples of cycloaddition arising by a [ 4 + 4] pathway are, as usual, relatively rare. Pyrid-2-one has recently been shown to yield four [ 4 +, 4] stereoisomeric dimers on irradiation in aqueous solution. A micellar alignment effect has been observed in related A-oj-carboxyalkylpyrid-2-ones on irradiation in micellar and reversed-micellar systems, the ratio of cis trans dimers has been found to increase with decreasing length of the alkyl chain. In the corresponding 4-alkyl derivatives, only cw-dimers were obtained. The reversible formation of [ 4 -l- 4] photodimers of benzo[g]quinoline and A -methylbenzo[g]-quinolinium has been reported. 

Unless otherwise stated, the Ps/oai. values were determined in 0.1 M KNO3 solutions at T = 30 °C by pH-potentiometric titrations. "SA, SSA and HQSA = salicylic, 5-sulfosalicylic and 8-hydroxy-quinoline-5-sulfonic acids, respectively oCA, mCA and pCA = 2-hydroxy-n-methylbenzoic acid (n = 3, 4 and 5, respectively). 

The palladium-catalyzed annulation of alkynes by a couple of other halo-amine/amide systems has been reported to provide a useful route to nitrogen heterocycles. For example, 8-dimethylamino-l-iodonaphthalene reacts with internal alkynes in the presence of a cyclopalladation catalyst to afford N-methylbenzo[d,c]quinolines (Eq.48) [110]. 

Hydroxy-3,8-dimethoxy-2-methylanthraquinone, in T-10161 1 -Hydroxy-5,6-dimethoxy-2-methylanthraquinone, in T-10160 7-Hydroxy-2,8-dimethoxy-1 -methyl-4-aza-9-fluorenone, in T-30198 7-Hydroxy-3,4-dimethoxy-5-methylbenzo[/z] quinolin-2(l/7)-one, see A-10131 7-Hydroxy-2,9-dimethoxy-4-methyl-6//-dibenzo[, f/]pyran-6-one, see S-10001... 

A soln. of 2-acetonaphthenone, 2-acetonaphthoxime (cis-methyl), and a little p-toluenesulfonic acid monohydrate in anhydrous benzene refluxed 3 days with azeotropic water entrainment using a Dean-Stark apparatus 2-( -naphthyl)-4-methylbenzo[h] quinoline. Y 40%. Limitations s. A. Rosenthal, J. Org. Ghem. 26,1638 (1961). 

A range of secondary A-alkylanilines undergo oxidative olefination with 2-alkyl-quinoline, 4-methylquinoline, 1-methylisoquinoline, 2-methylquinoxaline, 2-methyl-quinazoline, 2-methylbenzo[fiG-thiazole, acetophenone, and malononitrile in DMF to form structurally diverse polysubstituted alkenes in moderate to excellent yields with excellent E Z >99 1 selectivity with the use of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone as the oxidant. Mechanistically, the oxidative olefination reaction proceeds through amine oxidation followed by imine olefination." ii... 

When quinoline was allowed to react with diketene, 6a,7-dihydro-5,9-dimethylbenzo[f]pyrano[2,3-b]quinolizine-ll,12-dione (XXX) was formed and this on dehydrogenation gave (XXXI) [20]. The structure and reactions of (XXX) were also investigated [22]. In a similar manner, the isomeric system, 1 l-methylbenzo[a]pyrano[3,2-g]quinolizine-8,9-dione (XXXII), was synthesised by the reaction of isoquinoline and diketene [20]. 

A soln. of l,2,3,4-tetrahydro-N-methyl-l-oxo-2-naphthalenepropionamide in toluene containing p-toluenesulfonic acid refluxed 2-4 hrs. under a Dean-Stark water separator -> 3,4,5,6-tetrahydro-l-methylbenzo[h]quinolin-2(lH)-one. Y 80-90%. F. e. s. J. F. Bagli and H. Immer, J. Org. Chem. 35, 3499 (1970). 

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