Quinoline 1-oxides bromination

Quinoline, 2,4-bis(dimethylamino)-synthesis, 2, 419, 469 Quinoline, 3-bromo-bromination, 2, 319 oxidation, 2, 325 Skraup synthesis, 2, 467 Quinoline, 5-bromo-bromination, 2, 319 nucleophilic substitution, 2, 324 Quinoline, 6-bromo-nucleophilic substitution, 2, 324 Quinoline, 8-bromo-bromination, 2, 319 N-oxide... 

Quinoline N-oxide is brominated in the 3- and 6-positions on treatment with bromine in acetic anhydride, the mechanism probably involving an addition process in the hetero ring (65YZ62). 

Quinoline 1-oxide gives a 4-bromo derivative (Br2-H20,100°C). Isoquinoline 2-oxide is brominated in the 4-position by the mechanism of Scheme 13. 

In recent years, the reactivities of thieno[2,3-c]pyridine and its fused analogs have received considerable attention. Nitration of thieno[2,3-c]quinoline 5-N-oxide (225) gives rise to 1-nitro derivative 226 (1989CS305), whereas bromination affords a mixture of bromide 227 and dibromide 228 (1989CS309). 

Within a given series of heterocycles, differences in reactivity and stability are found compared to their corresponding benzo analogues (see Section 7.02.5). For example, 2,1-benzoisoxazoles are stable in mineral acids, while thieno[3,2-c]isoxazoles (1) and selenolo[3,2-c]isoxazoles (2) are not. Further, 2,1-benzoisoxazoles react with activated methylene synthons to afford quinoline V-oxides <67TL2337> whereas compounds (1) and (2) are inert. The isomer distribution from the pH dependent bromination of thieno[3,2-c]pyrazole (3) is similar to that found for indazole, while thieno[3,2-c]isoxazole (4) is relatively inert <76CS165,77CSi>. 

Carbon-sulfur bond formation by oxidative cyclization of a thiourea derivative using bromine will in the case of (521) furnish a thiazolo[/,/]quinoline (522 Z = NH). The same imine is obtained from 8-mercapto-l,2,3,4-tetrahydroquinoline on treatment with cyanogen bromide with phosgene the 2-oxo derivative (522 Z = 0) is formed (63JOC2581). 

Quinoline A -oxide gives a 4-bromo derivative (Br2H20, 100 C). Isoquinoline A -oxide is brominated at the 4-position... 

Domino [3+2] cycloaddition/annulation reactions of aminophenyl-ynones 23 with nitrile oxides, generated in situ from chloro oximes 22, allowed the synthesis of isoxazolo[4,5-c]quinolines 24, in satisfactory yields <03EJO1423>. Bromine substituents on naphthoquinones activate and orient 1,3-DC with nitrile oxides. Compound 25 reacted with halo oximes 22 to give regioselectively only unsymmetrical naphthoquinones 26, as polyketide building blocks <03TL8901>. 

Garcia et a/. cyclized the anti oxime 148 to the pyrrolo[l,2-a]quinoline 4-oxide 149 by use of one molar equivalent of bromine, and to the pyr-rolo[l,2-a]quinazoline 4-oxide 150 with formaldehyde in acetic acid. 

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