Ethyl quininate

Synthesis of Quinine. This required a parallel series of operations jn which the still unknown substance Aomomeroquinenine (3-vinylpiperi-dine-4-propionic acid) replaced its dihydro-derivative, Aomocincholoipon, for the final condensation with ethyl quininate. The first step was taken by ProStenik and Prelog,who converted cinchonine to cinchqnjcjn ... 

The first successful syntheses of quininic acid (CXXXVII, R = OCHt) were achieved independently in 1912 by Kaufmann and Peyer (183), and Pictet and Misner (184). The former group applied to 6-methoxy-quinoline the method which they had used earlier in the synthesis of cinchoninic acid from quinoline. Pictet and Misner isolated ethyl quininate in small yield directly from the condensation of p-anisidine with formaldehyde and pyruvic acid in the presence of hydrochloric acid. 

CLXXXIII). The same series of reactions was subsequently applied to ethyl quininate (205), which fumiehed dihydroquinotoxine. Some twenty-five years later partial synthesis of quinotoxine itself was achieved in like manner by ProStenik and Prelog (90), who condensed ethyl quininate with -benzoylhomomeroquinene ethyl ester, derived by Beckmann rearrangement from iV-benzoylcinchotoxine oxime. 

Resolution into optically active forms was not attempted at this point, but the product was converted into (tt-iV-benzoylhomomeroquinene ethyl ester and condensed with ethyl quininate in the presence of sodium ethonde. The dl-quinotonne obtmned on hydrolyms of the condensa tion product was resolved by crystallization (A the dibenzoyl-d-tartrates,... 

In 1946 Campbell et al. [6] synthesized ethyl quininate from / -anisidine and acetoacetate by heating the reaction mixture. It is an easy method to synthesize 6-substituted quinoline derivative in mild condition as compared to other method. 

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