3H-Indol-3-ols

A mixture of 3-hydroxy-3-phenyloxindole, 4-(3-aminopropyl)morpholine, and a catalytic amount of p-toluenesulfonic acid in xylene stirred and refluxed 10-15 hrs. under a Dean-Stark trap for azeotropic water removal -> 2-[(3-moropholinopro-pyl)amino]-3-phenyl-3H-indol-3-ol. Y 70%. - This reaction could not be performed in the absence of the free hydroxyl in position 3. F. e. s. R. F. Meyer and M. Zwiesler, J. Org. Chem. 33, 4274 (1968). 

Taguchi and associates (117) treated 3,3-dimethyl-3H-indole with p-chloroben-zoyl chloride in pyridine, and obtained two crystalline compounds in addition to l-(p-chlorobenzoyl)-3,3-dimethylindolin-2-ol. These two products had the molecular formula C27H25ON2CI, and a tricyclic structure with two benzo moieties was assigned. Dave and co-workers (118) questioned the structure on the basis of mechanistic considerations, and presented evidence that the products are atropisomers of 1 -(p-chlorobenzoyl)-2-(2,3-dimethyl-1 -indolyl)-3,3-dimethylin-doline (75) about the C—N axis. The barrier to rotation about the C—N bond... 

The 2H - and 3H -pyrroles and -indoles are considerably more basic than the corresponding 1//-isomers and they readily undergo alkylation to give the quaternary salts, which are then highly susceptible to nucleophilic attack. Thus, for example, methylation of the trialkyl-3//-indole (507), followed by reaction with aqueous base, yields the indolin-2-ol (508). A similar reaction sequence results from the acylation of (507) under Schotten-Baumann conditions to give (509 X = OH). When the benzoylation is conducted in benzene in the absence of the base, the 2-chloroindoline (509 X = C1) is formed and acylation of (507) with a carboxylic acid anhydride produces the ester (509 X = OCOR) (79HC(25-3)l). 

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