Synthesis of Pyrrolidine Ring of Nicotine from Several C14-labeled Metabolites by Nicotiana rustica

Studies on the Biosynthesis of the Pyrrolidine Ring of Nicotine*

“…If, however, short feeding periods were used such that the carbon of acetate would circulate through the tricarboxylic acid only a limited number of times, less and less 14C should be found in the 2 position, and more and more should be located in carbons 3 and 4. It was shown, however (Wu et al, 1962), that in feeding periods of 1, 2, and 3 hours, 18%, 20%, and 22%, respectively, of the 14C in the pyrrolidine ring was located in the 2 carbon. Recently Alworth et al (1964) administered 14C02 to tobacco plants to study the biosynthesis of nicotine, and estimated more 14C to be in the 3 and 4 positions of the pyrrolidine ring than would be expected if C02 were converted to glutamate through glycolysis and the tricarboxylic acid cycle.…”

“…Previous studies from our laboratory (Griffith and Byerrum, 1959;Wu et al, 1962) were concerned with the labeling of the pyrrolidine ring of nicotine following administration of 14C-labeled acetate, propionate, glycerol, and aspartate. When [l-14C]acetate was administered, essentially all of the 14C within the pyrrolidine ring was equally distributed between positions two and five.…”

“…Studies on the Biosynthesis of the Pyrrolidine Ring of Nicotine* Pei-Hsing Lin Wu and Richard U. Byerrum abstract : A degradation of nicotine which resulted in fission of the pyrrolidine ring to yield oxalic acid, methylamine, and 3-pyridyl methyl ketone was developed, which, along with previously utilized degradations, permitted assessment of 14C in each carbon of the ring. After a biosynthetic period of 2 days with [2-14C]acetate, radioactivity was found to be evenly distributed WZÍen [l-14C]acetate (Wu et al, 1962) or [2-14C]glutamate (Lamberts and Byerrum, 1958) was administered to tobacco plants, the nicotine synthesized was labeled equally in the 2 and 5 positions of the pyrrolidine ring, and little or no 14C was incorporated into the 3 and 4 positions. This labeling pattern was consistent with the hypothesis that acetate was converted by way of the tricarboxylic acid cycle to glutamate which then yielded the pyrrolidine ring through a symmetrical intermediate (Lamberts and Byerrum, 1958;Leete, 1958).…”

“…This labeling pattern was consistent with the hypothesis that acetate was converted by way of the tricarboxylic acid cycle to glutamate which then yielded the pyrrolidine ring through a symmetrical intermediate (Lamberts and Byerrum, 1958;Leete, 1958). When additional14C-labeled precursors, such as [2-14C> acetate, [2-14C]propionate, or [l,3-14C]glycerol (Wu et al, 1962), were fed to tobacco plants, the nicotine synthesized was labeled in all of the carbons of the pyrrolidine ring. In these experiments, therefore, it was not possible to test the proposed biosynthetic pathway involving the tricarboxylic acid cycle until a degradation could be developed which would permit an estimation of 14C in each ring carbon.…”

Optical Rotatory Dispersion Studies. CVII.1 Factors Governing the Relative Stability of Hydrindanones. Syntheses of 17-Alkyl-15-keto Steroids2

“…Initially it was hoped that a 1,4-Grignard9 addition to A16-5a-androsten-15-one (XXVIII)4® in the presence of cuprous acetate would give the desired 17/3-methyl-5aandrostan-15-one (XXXIV). Failure to obtain any I, 4-addition product by this method necessitated the use of an alternate route to 15-keto steroids, and the introduction of a benzyloxy group at C-1510 from readily prepared A15-17-keto steroids (e.g., VII) ap- (7) For a detailed literature survey see the literature citations in (a) M. Hanack, "Conformational Theory," Academic Press Inc., New York, N. Y" 1965, pp 177-180 and (8) For citations to these reactions see footnotes 15 and 16 in ref 4g. (9) Cf.…”