Bases of the Laudanosine Type

Laudanine has the formula C20H26NO4. It reacts basic but goes into solution in excess alkali. This behavior, as well as its color reaction with ferric chloride, suggests the presence of a phenolic hydroxyl group. In concentrated sulfuric acid the compound turns red, the color changing to violet on heating to 150 . 

Laudanine is optically inactive in spite of the presence of an asymmetric 

The following salts of laudanine have been described hydrochloride, sulfate, oxalate, tartrate, platinichloride, aurichloride, picrate (m.p. 176-177°), and the sodium salt. 

Methylation with methyl iodide (93) or diazomethane (86) yields dl-laudaiiosine (XIII). Likewise, ethylations with ethyl iodide, ethyl sulfate (84), or diazoethane furnish 3 -ethyllaudanine. Oxidation of this ethyl ether ruptures the molecule, and Spath (86) was able to isolate 3-ethoxy-4-methoxybenzoic acid from the reaction mixture, thus locating the position of the hydroxyl group in laudanine. 

Protection of the phenolic hydroxyl group during the oxidation can also be effected by carbethoxylation. 

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