Synthesis and Use of Deuterated Palmitic Acids to Decipher the Cryptoregiochemistry of a Δ13 Desaturation

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Abstract
5 pages, 3 figures.-- PMID: 17253792 [PubMed].-- Supporting information (Additional methods and procedures, 63 pages) available at: http://pubs.acs.org/doi/suppl/10.1021/jo061592s/suppl_file/jo061592ssi20061124_060211.pdfThe synthesis of two hexadeuterated palmitic acids differing in the position of the diagnostic labels, and their use to decipher the cryptoregiochemistry of a Δ(13) desaturation are described. A dithiane and a triple bond functionalities were used to introduce the diagnostic (C13 or C14) and tagging (C8 and C9) labels, respectively, in the palmitic acid skeleton. Using these probes, the cryptoregiochemistry of the Δ(13) desaturation involved in the biosynthesis of Thaumetopoea pityocampa sex pheromone was studied by means of kinetic isotope effect determinations. Transformation of both (Z)-11-hexadecenoic and 11-hexadecynoic acids into (Z, Z)-11,13-hexadecadienoic and (Z)-13-hexadecen-11-ynoic acids, respectively, is initiated by abstraction of the hydrogen atom at the C13 position, followed by the fast elimination of the C14 hydrogen to give the double bond.We gratefully acknowledge CICYT and FEDER (Grant AGL2001-0585) and Generalitat de Catalunya (Grant 2005SGR00726) for financial support. J.-L.A. thanks Spanish MEC for a Ramón y Cajal contract. The authors also acknowledge Rodolfo Hernández from Laboratorio de Sanidad Forestal (Gobierno de Aragón Mora de Rubielos, Teruel) for\ud providing T. pityocampa female pupae.Peer reviewe