Total Synthesis of a Potent Proinflammatory 5-Oxo-ETE and Its 6,7-Dihydro Biotransformation Product

The first total synthesis of a potent inflammatory mediator 5-oxo-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid (5-oxo-ETE) 2 and its biotransformation product 6,7-dihydro-5-oxo-ETE 5 is reported. A convergent synthesis for the unstable title compounds is accomplished via two synthons, dithiolane aldehyde 13 and bisdienyl phosphonium bromide 19. The synthetic 5-oxo-ETE 2 and its 8,9-trans isomer 3 were used to unequivocally confirm the structure of the biologically derived mediators. In addition, using synthetic 6,7-dihydro-5-oxo-ETE 5 we have been able to identify in neutrophils the formation of 6,7-dihydro-5-oxo-ETE 5.