Nemorensine

Analytical Letters, 2006 , 22 (15) :3041-3055.

Indirect Determination of Pyrrolizidine Alkaloids by Flame Atomic Absorption Spectrometry[Reference: WebLink]

This paper studies the formation and extraction of ion pairs of some alkaloids derived from pyrrolizidine.
METHODS AND RESULTS:
The substances studied are Nemorensine, Platyphylline, Senecionine and Seneciphylline, and the ion pairs studied and extracted are formed with Bil4. The method consists of extracting an ion pair between the organic base and the inorganic complex, the metal is measured in the organic phase (1,2 dichloroethane) by Flame AAS. The optimal experimental conditions, pH, concentration of BiI4 , shaking time, phase ratio, number of extractions, and the range of calibration are studied for these substances. The linear range in organic phase is 0.13–1.91 mg.mL.
CONCLUSIONS:
The standard deviation of the method varies between 2.4–3.2%, depending on the substance analyzed. The interferences produced by various substances are studied.

J Org Chem. 1999 Jul 23;64(15):5542-5546.

Enantiospecific Synthesis of (+)-Nemorensic Acid, a Necic Acid Component of the Macropyrrolizidine Alkaloid, Nemorensine.[Pubmed: 11674618]

METHODS AND RESULTS:
A concise enantiospecific synthesis of nemorensic acid 3, a necic acid component of the macropyrrolizidine alkaloid Nemorensine 2, isolated from Senecio nemorensis L., is described. Reaction of an epsilon-halo-alpha,beta-unsaturated ester (8), readily accessible from a monoterpene (-)-carvone, with samarium iodide gave a fragmentation product (9), where a carbon-carbon bond cleavage reaction occurred between the gamma and delta positions of the carbonyl group, regioselectively.
CONCLUSIONS:
Deprotection of the silyl group of 9 brought about an intramolecular cyclization to provide tetrahydrofuran derivatives (10), which, upon chemical modification of the side chain, gave nemorensic acid.