Selective Epoxidation of Eicosa-cis-5, 8, 11, 14-tetraenoic (Arachidonic) Acid and Eicosacis-8, 11, 14-trienoic Acid

The key role of arachidonic acid (1) as the predecessor of a large family of biologically important substances including prostaglandins (PG's), thromboxanes, SRS-A, HETE, and prostacyclin (members of the “arachidonic cascade”) depends on highly selective enzymatic oxidation of this substrate as a primary event. Similarly, selective oxidation of eicosa-cis-8, 11, 14-trienoic acid (2) initiates the series of transformations leading to PG₁derivatives. Despite the great interest in such controlled biological oxidations of 1 and 2, and despite the obvious utility of the primary oxidation products as intermediates for the synthesis of various metabolites of 1 and 2, there has been no demonstrated example of selective chemical oxidation of these polyunsaturated substrates. This communication describes the first successful approach to this chemical problem, specifically new methodology for epoxidation of either the double bond closest or farthest from the carboxyl function of 1 or 2.