8-Phenylbenzo quinoline

Heeramaneck and Shah obtained 3-phenylbenzo[/]quinoline-2-carbox-ylate (908) in good yield on the ring closure of diethyl phenyl(2-naphthyla-mino)methylenemalonate by heating in the melt at 185-195°C (37JCS867). 

Certain aromatic imines undergo a similar cyclodehydrogenation to the phenanthridine. Benzylideneaniline (330) yields phenanthridine (331) only in sulfuric acid,355 whereas diphenylmethyleneaniline cyclizes in the presence of oxygen or iodine.356 Cyclizations have also been reported in Schiff s bases formed from a- and /J-naphthylamine357 and from 4-aminoquinoline,358 and in the mesomeric betaine 4,5-diphenyl-2-mercapto-l,3,4-thiadiazolium hydroxide.359 Irradiation of the anil of 2-aminonaphthalene (332) in ethanol, however, leads to incorporation of ethanol and the formation of 3-phenylbenzo[/]-quinoline (333).860 Additional photoproducts are obtained when the photolysis is carried out in w-hexanol.361... 

A series of 2,3-substituted l-phenylbenzo[/]quinolines 10 was synthesized from l-benzoyl-2-naphthylamine 9 with p-keto esters, 50-88% yields (Scheme 5) (68JHC313). 

A reaction which could involve the vinyl alcohol tautomer of acetaldehyde is the synthesis of 2-(2-naphthyl)quinoline by photolysis of the anil (393) in ethanol (68TL3685). From the benzaldehyde anil of a-naphthylamine by a similar reaction, 2-phenylbenzo[Jt]quinoline... 

Irradiation of 3-chloro-A-phenylbenzo[Z ]thiophene-2-carboxamide and triethylamine in benzene/methanol (4/1) yielded [l]benzothieno[2,3-c]quinolin-6(5//)-one (92%)597. 

A totally different approach to the tricycle is based on the desulphurisation of hexahydro-4S-benzo[d,e]benzothieno[2,3-g]quinolines (88) which leads to the corresponding 8-phenylbenzo[d,e]quinoline (89) or the partially oxidised derivative (90). The... 

Zinc(II) chloride-tetramethylethylenediamine complex (4.23 g, 16.7 mmol), 1,10-phenanthroline (101 mg, 0.56 mmol), and benzo[/t]quinoline (1.00 g, 5.6 mmol) are placed in a Schlenk tube. To this mixture a solution of phenylmagnesium bromide (33.5 mL, 1.00 M, 33.5 mmol) in tetrahydrofuran is added dropwise at 0 °C. After stirring for I h, a 0.1-M solution of tris(acetylacetonato)iron in tetrahydrofuran (5.6 mL, 0.56 mmol) and 1,2-dichloro-2-methylpropane (1.42 g, 11.2 mmol) are sequentially added. The reaction mixture is stirred at 0 °C for 16 h and is quenched by the addition of a saturated aqueous solution of sodium bicarbonate (40 mL). After extraction with ethyl acetate (25 mL, 3 times), the organic layer is dried over sodium sulfate and concentrated under reduced pressure. The crude product is purified by silica gel chromatography (eluent first hexane to elute the biphenyl, then toluene) to afford 10-phenylbenzo[A]quinoline as a colorless solid mp 90.6-92.5 1.39 g (98%). ... 

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