Pilopic acid

CHsjOH. CHlCgHg). CH(COOH). CH. COOH COOH. CHlCgHg). CH(CHaOH). CH. COOH COOH. CH(C2Hg). CH(COOH). CH. CH OH AomoPilopic acid is very stable, and is probably therefore the y-lactonic acid of one of these three hydroxy-acids. Further, pilopic acid seems to be produced from its higher homologue by loss of carbon dioxide and oxidation of the contiguous carbon atom. Of the four y-lactonic acids derivable from these three hydroxy-acids only two (I and II) answer these conditions,... 

As a substance of formula (HI) should lose carbon dioxide on heating, whereas pilopic acid is stable even at 200°, it seemed probable that homo-pilopic acid is represented by (II) and pilopic acid by (IV). Jowett also showed that pilocarpine, like wopilocarpine, yields Aomopilopic acid when oxidised by permanganate.In the oxidation of the two alkaloids the two nitrogen atoms are eliminated as ammonia and methylamine. 

N. A. Freobrashenski (69). On resolution through the strychnine salt, the d- and i-forms were obtained, the former being identical with d-iso-pilopic acid obtained by the oxidation of isopilocarpine and purified through the strychnine salt. The solid ester (XXXIII) similarly gave dZ-pilopic acid, which is readily isomerized to dZ-isopilopic acid when heated (61). It was resolved through the brucine and cinchonine salts (62). 

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