Efficient total synthesis of 5-oxo-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid (5-oxo-ETE), a potent proinflammatory autacoid

Structure Revision and Syntheses of Epohelmins A and B

[structures: see text] Epohelmins A (24) and B (26) have been reassigned as pyrrolizidin-1-ols, rather than the proposed 9-oxa-4-azabicyclo[6.1.0]nonane structures 1 and 2, respectively. Syntheses of epohelmin A (24) (eight steps, 52% overall yield) and epohelmin B (26) (11 steps, 43% overall yield) have been achieved starting from N-Cbz-(S)-prolinal (9) and ortho ester ketone 17 using a stereoselective aldol reaction and a stereoselective reductive cyclization as the key steps.