Brucinonic acid

The Na lactam in strychninonic acid (XXXVIII) (50) and brucinonic acid (51) opens with boiling 5 N hydrochloric acid for 30 minutes or with 1 N NaOH at 0° for 48 hours. The alkaline hydrolysis was only reported for brucinonic acid it is interesting to note that, under these conditions, some elimination of glycolic acid also occurs (cf. Section II, B, 3). 

Brucinonic acid (2,3-dimethoxy XXXVIII) is reduced to two isomeric dihydrobrucidinonic acids (XLII), C-21 epimers, in which the Na lactam carbonyl, but not the Nb lactam carbonyl, has been reduced the ketone carbonyl is concurrently reduced to the epimeric alcohols (60, 109). It would seem that electrolytic reduction to CH2 is a special property of the Na lactam carbonyl group. 

Further examples are the oxidation of CXXXI (R = H or OCH3) to CXXXII in 30-40% yield (119), and of brucinonic acid (2,3 dimethoxy XXXVIII) to two C13 amino acids (CXXXIII and CXXXIV) in the extremely poor yield of about 0.5% (22,120). This reaction also involves the oxidative breakdown of the Nb a-ketoamide ring. 

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 electrolytic reduction of brucinonic acid at a lead cathode reduces Ng-CO —> Na-CHi-and the ketone to an alcoholic hydroxyl the resulting stereoisomeric brucidinolic acid and dihydrobrucidinonic acid show typical brucidine reactions (122). 

Brucinone, the ketone of brucinolone-a, contrary to expectation is not readily available, if at all, from the alkaline cleavage of brucinonic acid (61, 100) or from its derivatives (oxime (95, 105), hydrazone (100), phenyl-hydrazone (102), and semicarbazone (102)). However, strychninone (236) and dihydrostrychninone (190, 232, 236) (XXVII) have been prepared by another method. The secondary hydroxyl of strychninolone-a and of dihy-drostrychninolone-a (from the catalytic reduction of strychninolone-a) has been oxidized (CrOs) to a ketonic group. 

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. 

Brucinone (see Dehydrobrucinolone) Brucinonic Acid 245 Needles (HOAc) 61... 

---