Abstract
When a phenylhydrazine is reacted with phenylacetone or methyl ethyl ketone, the reaction using hydrogen chloride, zinc chloride, ortho-phosphoric acid or boron trifluorideetherate as a condensing agent gives 2-methyl-3-phenylindole or 2, 3-dimethylindole respectively, but the reaction using polyphosphoric acid affords the above-mentioned 2-methylindole derivative as well as 2-benzyl- or 2-ethyl-indole respectively, amount of which product tends to increase with increasing a ratio of phosphorous pentoxide to ortho-phosphoric acid. In reacting a N1-(p-chlorobenzoyl) phenylhydrazine with phenylacetone, the reaction in the presence of every catalyst gives 2-methyl-3-phenylindole derivatives as a main product, and even when used polyphosphoric acid it is too difficult to yield 2-benzylindole derivative. Several mechanisms on these results are suggested.
