DZ-Tropic acid

When heated with acids or alkalis, hyoscyamine undergoes hydrolysis into tropine and dZ-tropic acid probably via conversion into atropine, and it is this alkaloid which is hydrolysed. According to Gadamer, when hyoscyamine is hydrolysed with cold water the products are inactive tropine and Z-tropie acid. Amenomiya has shown that Ladenburg and Hundt s partially synthetic d- and Z-atropines were probably mixtures of atropine with d- and Z-hyoscyamines. He resolved dZ-tropic acid into the d- and Z- forms, esterified these with tropine in 5 per cent, hydrochloric acid, and so obtained d- and Z-hyoscyamines, the latter identical with the natural alkaloid, d- and Z-Hyoscyamines have also been obtained by Barroweliff and Tutin by the resolution of atropine by means of d-camphorsulphonic acid. 

The ease with which Z-hyoscyamine is racemized by alkali would suggest (235) that atropine is the intermediate in the hydrolysis of Z-hyoscyamine to tropine and dZ-tropic acid. If Z-hyoscyamine is hydrolyzed in water (60) tropine and Z-tropic acid are formed. From this it would appear that the optical activity of this Zeworotatory alkaloid may be attributed to the asymmetry of the tropic acid residue or that racemization of the tropine during hydrolysis has occurred. This last assumption apparently is not valid for all attempts to resolve tropine have failed (205). 

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