Carbon Dioxide → [1-(p-Chlorobenzoyl)-5-methoxy-2-methyl-3-indoleacetoxy]-benzyl acetate

Participants

Reaction Steps

Another method of preparing the compound I according to the invention is the acylation of (5-methoxy-2-methyl-3-indoleacetoxy)-benzyl acetate and subsequently splitting off the benzyl group. The mixed anhydride of p-chlorobenzoic acid with a monoalkyl ester of carbon dioxide is preferably used as acylation agent for this purpose. The reaction takes place by simply mixing the reactants and slowly heating them to 200°C until the evolution of carbon dioxide, starting at about 80°C, has ended. It is advantageous to use an excess of anhydride, preferably in the ratio of 1:2 to 1:3. The reaction takes place in the presence of a catalytic quantity of an organic base. As the organic base it is possible, inter alia, to use quinoline and pyridine and, more particularly triethylamine. The subsequent hydrogenation of the [1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indoleacetoxy]-benzyl acetate which is formed takes place as described under A.

Provenance & Evidence