title: First total synthesis of (5Z,9Z)-(+/-)-2-methoxy-5,9-octadecadienoic acid, a marine derived methoxylated analog of taxoleic acid.
abstract: The first total synthesis for the sponge derived (5Z,9Z)-(+/-)-2-methoxy-5,9-octadecadienoic acid, an analog of taxoleic acid, was accomplished in seven steps and in a 10% overall yield. It was again corroborated that the best strategy to prepare these cis,cis dimethylene interrupted double bonds is the double-alkyne bromide coupling reaction of 1,5-hexadiyne, which provides the advantage of achieving a 100% cis stereochemical purity for both double bonds after hydrogenation under Lindlar conditions. The alpha-methoxy functionality was best prepared via the Mukaiyama reaction of (4Z,8Z)-heptadecadienal with trimethylsilyl cyanide and triethylamine followed by acid hydrolysis. Selective methylation of the hydroxyl group of (5Z,9Z)-(+/-)-2-hydroxy-5,9-octadecadienoic acid was achieved with sodium hydride/methyl iodide when tetrahydrofuran was used as solvent. Complete spectral data is presented, for the first time, for this unusual marine alpha-methoxylated fatty acid.
authors.affiliation: Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346, USA. nmcarballeira@uprrp.edu
authors.forename: Néstor M
authors.initials: NM
authors.lastname: Carballeira
authors.forename: Rosann
authors.initials: R
authors.lastname: O'Neill
authors.forename: Diana
authors.initials: D
authors.lastname: Silva