6- Bromo-5-hydroxy indole

Bromo-16-hydroxy-8,17,19-tricosatriene-4,6-diynoic acid, in B-30087 6-Bromo-l//-indole-3-acetamide, in B-20046 6-Bromo-l//-indole-3-acetic acid, B-20046 6-Bromo-l//-indole-3-acetonitrile, in B-20046... 

Bromo-l//-indol-3-yl)(phenyl)methyl)-4-hydroxy-6-methyl-2//-pyran-2-one (4bc) Deep brown solid, mp 110-112 °C yield 60%... 

Indole-2-carboxylic acid, 5-bromo-l-hydroxy-tautomerism, 4, 197-198 Indolecarboxylic acid chloride synthesis, 4, 288... 

CPB3678) and the ester (Table IV) show that these compounds exist entirely as the hydrogen-bonded 1-hydroxy tautomers, but in contrast, 3-bromo-l-hydroxyindole-2-carboxylic acid appears to favor the 3H-indole 1-oxide form [68JCS(C)504]. Only the 1-hydroxy tautomer was observed in a number of cases in deuteriochloroform and in hexadeuterio-dimethylsulfoxide solutions (83JOC3639). 

Dehydrobromination of 5-bromo-4-oxo-1-(4 -toluenesulphonyl)-4,5,6,7-tetra-hydroindole with lithium bromide in dimethylformamide at 150"C during 1 hour gave in 97 /o yield, 4-hydroxy-1-(4 -toluenesulphonyl)indole (ref.49). 

Hydroxyindole does not exist as such the stable form is the carbonyl tautomer the hydroxy tautomer cannot be detected. There is nothing remarkable about the reactions of oxindole, for the most part it is a typical 5-membered lactam, except that deprotonation at the /3-carbon (p fg 18) occurs more readily than with simple amides, because the resulting anion is stabilised by an aromatic indole canonical contributor. This anion will react with electrophiles like alkyl halides and aldehydes at the /3-carbon, the last with dehydration and the production of aldol condensation products. It is interesting that the 3-position is three times more reactive than the 1-position. Oxindoles can be effectively oxidised to isatins (section 17.14.3) via easy 3,3-dibromination, then hydrolysis. Bromination of oxindole with A -bromosuccinimide gives 5-bromo-oxindole. ... 

Under similar reaction conditions, 35 generates many products such as 7-bromo- (59), 2,7-dibromotryptamines (60), 57, 7-bromo- (61), 5-bromo-2-oxindoles (62), 56,2-bromotryptamine (63), and 58, depending on the bromination conditions (entries 1-3). l-Hydroxy-Wh-methoxycarbonyltryptamine (52) shows almost the same results as 35. It should be noted that the ratio of all of the 7-brominated indoles to the total products, observed in the bromination of 1-hydroxyindole derivatives (35 and 52), is much higher than that of the N(l)-H compound (55). 

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