The constitution of scopoletin / by Charles W. Moore.

  • Moore, Charles W.
Date:
[1911?]
Catalogue details

Licence: In copyright

Credit: The constitution of scopoletin / by Charles W. Moore. Source: Wellcome Collection.

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    On attempting to prepare the substituted coumaric acid from scopoletin by the prolonged action of aqueous potassium hydroxide on the latter, it was found that oxidation took place, with the production of a dihydroxymethoxybenzene. Only two possibilities can here exist, and the product of the reaction must be either 2:5- or 2 :4-dihydroxyanisole, according as scopoletin is the 4- or 5-methyl ether of aesculetin. As the phenol obtained was found to be the 2 :4-dihydroxy-compound, its formation from scopoletin must be represented as follows: CHICH-CO ch:ch-co2h /Vo-1 //oh * MeOl^J — MeOl / —> OH OH (III.) (IV.) C0oH ( /oh ( |OH MeOi \ --> MeOl^j + OH OH (V.) (VI.) + COr Scopoletin must, therefore, be 4-hydroxy-5-methoxycoumarin, whilst the other monomethyl ether of aesculetin, melting at 184°, which has only been obtained synthetically, will be 5-kydroxy- 4-metkoxycoumarin. The identification of the above-mentioned 2:4-dihydroxyanisole was effected by means of its analysis and melting point, and by the preparation of its diacetyl derivative, which melts 30° lower than 2 :5-diacetoxyanisole. Attempts to isolate the 2 :4-dihydroxy-5-methoxybenzoic acid (V), which must be formed as an intermediate product, were unsuccess¬ ful, and it appears probable that this substance, when liberated from its salts, loses carbon dioxide with the formation of the corresponding dihydroxyanisole. Although the prolonged action of aqueous potassium hydroxide on scopoletin had been found to result only in the formation of a phenol, it has been ascertained that if the alkali is allowed to act for a few minutes only, an almost quantitative yield of 2 : k-dihydroxy-b-methoxycinnamic acid is obtained. Sodium deriva¬ tives of this acid have already been described by Kunz-Krause (loc. cit.), who, however, does not appear to have prepared the free acid. A number of derivatives of this substance have now been prepared, which are described in this paper. The ease with which scopoletin is hydrolysed is' remarkable, as coumarin is only very slowly converted into o-coumaric acid by
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