THE BIOSYNTHESIS OF TROPIC ACID .6. ENANTIOSELECTIVE, INTACT INCORPORATION OF (R)-(-3-PHENYLLACTIC ACID INTO THE TROPIC ACID EATER ALKALOIDS OF DATURA())

(R)-((+))- 11 and (S)-((-))-3-Phenyl[1,3-C-13(2); 1-C-14]lactic acid 1 3 were fed separately to Datura stramonium (Solanaceae) via the wick m ethod. In a second feeding experiment (R)-((+))- and (S)- ((-))-3-phen yl[1,3-C-13(2); 2-C-14]lactic acid were administered via the roots. In both cases hyoscine (scopolamine) and hyoscyamine 1 and 2, respective ly were isolated separately from the roots and aerial parts. The (R)-e nantiomer 11 was more efficiently incorporated into the (S)-((-))-trop ic acid 8 moiety of both bases. Examination of the C-13 NMR spectra of the bases and of tropic acid, obtained by hydrolysis of hyoscyamine, showed C-13-C-13 spin-spin coupling indicating that the tropoyl ester ((-))-hyoscyamine 9 is formed by direct rearrangement of the (R)-((+)) -3-phenyllactic acid 11 ester of tropine (littorine).