A new synthesis of the F5 furan fatty acid and a first synthesis of the F6 furan fatty acid

Anne B Evans,David W Knight,Susanne Flügge,Simon Jones,Wen-Fei Tan,John Arthur Joule

doi:10.3998/ark.5550190.0009.a08

Abstract

Total syntheses have been achieved of the two furan fatty acids F5 and F6 1, in which the central step features generation of the furan ring using either iodine or silver-induced 5-endo-dig cyclisations of suitably functionalized 3-alkyne-1,2-diols.

Highlights

The furan fatty acids F5 and F6, 1a and 1b, are unusual in that they contain respectively a tri- and a tetra-substituted furan core; most furanoid fatty acids are 2,5-disubstituted compounds.[1]
First identified in Exocarpus cupressiformis seed oil,[2] they occur in fish oils where they may be associated with reproductive cycles,[3] and are found in marine sponges,[4] and in many plant species, which inevitably means they are present in many foods.[5]
While their precise role remains unclear, urofuran acids [structure 1, but CO2H in place of the 3-methyl group], which occur in human urine are likely metabolites of these natural products.[6]

Summary

Introduction

The furan fatty acids F5 and F6, 1a and 1b, are unusual in that they contain respectively a tri- and a tetra-substituted furan core; most furanoid fatty acids are 2,5-disubstituted compounds.[1]. The βmethyl was introduced by a second Pd(0)-catalysed coupling with tetramethyltin acting as the carbon source and the synthesis was completed by hydrogenation of the two unsaturated linkages and ester hydrolysis.[9] As far as we are aware, there has been no report of a synthesis of furan fatty acid F6 1b

Results

Conclusion