Synthesis from arachidonic acid of potential prostaglandin precursors

Abstract

Arachidonic acid has been converted by aerobic oxidation with lipoxygenase (ex soybean) as catalyst and in the presence of sodium borohydride in a one-pot procedure (1 g scale) into (5Z,8Z,11Z,13E)(15S)-15-hydroxyeicosa-5,8,11,13-tetraenoic acid. The methyl (15S)-15-hydroxyeicosatetraenoate or its p-nitrobenzoate derivative may be epoxidised with m-chloroperbenzoic acid to afford mixtures of the 5,6-, 8,9-, 11,12-, and 13,14-monoepoxides together with a mixture of bisepoxides. The methyl (15S)-15-(p-nitrobenzoyloxy)eicosatetraenoate epoxides can be separated by preparative t.l.c. The methyl (15S)-15-(mercaptoacetoxy)eicosatetraenoate has been prepared from the chloroacetate derivative of the methyl (15S)-15-hydroxyeicosatetraenoate by reaction with potassium thioacetate followed by selective hydrolysis of the thioester function.