Quinoline ozonolysis

Ozonolysis of 5,8,9-trihydroxy-2,3-dihydro-l//-pyrimido[l, 2-n]quinoline-3-carboxylic acid (420), obtained from isopyoverdin isolated from Pseudomonas putida BTPl by acidic hydrolysis, gave l-2,4-diaminobutyric acid, which confirmed the hypothesis that heterocyclic chromophores 1 and 4 of pyoverdin and isopyoverdin, respectively, could have the same precursor, and the configuration at C(3) should be 5 (97ZN(C)549). 

Opening of the benzo ring of quinoline can be achieved with a large variety of oxidizing agents. Ozonolysis at -25 °C proceeds by a primary attack at the 5,6- and 7,8-bonds,... 

Benzo ring cleavage of acridine results from oxidation with permanganate, the product being quinoline-2,3-dicarboxylic acid (acridinic acid), which is also the main product of ozonolysis in methanol (Scheme 26) (64JA38). 

Ozonolysis of phenanthridine in methylene chloride followed by alkaline peroxide oxidation gives quinoline-3,4-dicarboxylic acid (2%) and phenanthridone (39 23%) as the main product (Scheme 27) (64JA38). 

Ozonolysis of quinoline gives glyoxal and pyridine-2,3-dicarboxaldehyde. 

Ozonolysis of quinoline gives glyoxal and pyridine-2,3-dicarboxaldehyde similarly, 3-fluoroquinoline is converted into 5-fluoropyridine-2,3-dicarboxylic acid, for example, using ozoneH202 (Scheme 82) <2001S2495>. 

The quinoline 88 has been transformed into the intermediate 89, which was subsequently ring-opened by ozonolysis, followed by base-induced ring closure to the indole-2-carboxaldehyde 90 (Scheme 60) <2002TL5295>. Several useful 4-substituted indoles have also been prepared by ring-contraction of A-alkyl-5-aminoisoquinolinium salts with the system NaHS03/Na2S03 <2000JHC1293, CHEC-III(3.0340)333>. 

EtOH), were first isolated in 1872 and 1877, respectively (14). Quin-amine was observed to give indole color reactions (7, 15), and 2,3-dimethylindole was a result of zinc dust distillation of the alkaloid (15). With chromic acid (9), the quinuclidine carboxylic acid (III) was obtained, and with nitric acid 3,6,8-trinitro-4-hydroxyquinoline was isolated (15, 16). This quinoline is a consequence of fission of the indole and recyclization, with nitration preceding and following these steps [cf. ozonolysis of yohimbine to furnish a 2,3-disubstituted 4-hydroxy-quinoline (17)]. 

A four-step synthesis of 8-amino-7-quinoline carbaldehyde (87) from 8-hydroxyquinoline (88) has been disclosed (Scheme 48) (94T(50) 10685). Major steps involved a Bucherer reaction followed by Claisen type rearrangement, isomerization and ozonolysis. Amino aldehyde (87) underwent Friedlander condensation with 2-acetylpyridine to form 2-pyridyl-l,10-phenanthroline (89). 

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