The absolute stereochemistry of lactobacillic acid was confirmed as being 1 lR,12S, by mild oxidation of the synthetic fatty acid (A) forming two ketones, and the comparison of the analytical data for the ketones to literature data.
0 HO A0HO~,,,·~B
Cascarillic acid was synthesised, and all data for the synthetic cascarillate (B) was in agreement with that of a natural sample, proving its stereochemistry to be 3S,4R.
Dihydrosterculic acid (C), dihydromalvalate (D), the C11 cyclopropane fatty acids (E and F), the C15 fatty acid (G) and the C13 fatty acid (H) were all synthesised for use as standards in the determination of the absolute stereochemistry of the cyclopropane components of the seed oils of Litchi chinensis and Euphoria Longan.
HOHOG H
The absence of dihydromalvalate (D) in the seed oils was confirmed by GC-MS,
which also showed that the C15 (G) and C13 (H) cyclopropane fatty acids were absent from the samples extracted for this study, contrary to expectations.
Following the synthesis of a chiral resolving agent and the derivatisation of the
synthetic and natural samples, HPLC at -50 °C confirmed the absolute
stereochemistry of dihydrosterculate as 9R, 1 OS-methyleneoctadecanoic acid ( J), and showed the absolute stereochemistry of the C17 cyclopropane fatty acid to be 7R,8Smethylenehexadecanoic acid (K).
0 6 0 6HO~,,.· ··,,~ HO~,,.· ·,,~J K
Tuberculostearic acid and its enantiomer were synthesised using a chiral pool
strategy, starting from S and R citronellyl bromide. The stereochemistry of
tuberculostearate was confirmed as lOR-methyleneoctadecanoic acid by the
comparison of the optical rotation values of the two synthetic samples to literature data.