On the next stage, the ethyl ester of N-benzoylhomomeroquinene (184.108.40.206) is condensed with the ethyl ester of 6-methoxyquinolinic acid (220.127.116.11) in the presence of sodium ethoxide to make a derivative of quinotoxin (18.104.22.168). Boiling this in hydrochloric acid results in hydrolysis of the carbethoxy and benzoyl groups, and simultaneous decarboxy-lation gives the compound (22.214.171.124). Treating this with sodium hypobromite makes an
N-bromo derivative (126.96.36.199), which is reacted with sodium ethoxide realizing the key moment of the synthesis—the transformation of the piperidine derivative to a quinuclidine derivative (188.8.131.52). Reducing the keto group in this molecule with lithium aluminum hydride gives the desired quinine (184.108.40.206) [17-22].
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