Dihydrobrucinonic acid

Brucinonic acid and dihydrobrucinonic acid are similarly constituted but the carbonyl group of the former is replaced by an alcoholic hydroxyl group (acetyl derivative (71) and oxidation to brucinonic acid (55)) in the latter. Contrary to expectation, brucinonic acid is not reduced (NaHg in acid medium (57, 69, 122) ) to dihydrobrucinonic acid but to the stereo-isomeric brucinolic acid. These changes may be schematically represented as follows ... 

The dimethoxybenzene nucleus of brucine (159), its methosulfate (82), dihydrobrucine (159), the brucinesulfonic acids (60, 93), pseudobrucine and its dihydro derivative (162, 165), iV-methyl-sec-pseudobrucine (168) as well as that of a number of transformation products of brucine (brucinonic acid (126), brucinolic acid (126), dihydrobrucinonic acid (126), bromo-dihydrodesoxybrucine (32), and dihydrodesoxybrucine (32)) is attacked by nitric acid (chromic acid in a few instances) at 0-5° with the formation of the respective o-quinones, which in turn may be reduced (SO2) to the respective colorless hydroquinones (or isomerized by HCl to colored isomers). More vigorous conditions (temperature and concentration of the oxidant) effect a simultaneous nitration of the quinone nucleus and a hydrolysis of the lactam grouping. 

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