Convergent and enantioselective syntheses of both enantiomers of (5Z)-tetradecen-4-olide, scarab beetle pheromones

Japonilure and its enantiomer, that is, (R)-(-)- and (S)-(+)-(5Z)-tetradecen-4-olide, have been synthesised in satisfactory overall yields using a highly convergent procedure. In situ prepared 1-decynylethylzine was enantioselectively coupled to isopropyl 4-oxobutanoate in the presence of (S)- or (R)-BINOL. The alkoxy-ester intermediates obtained were cyclised to the corresponding substituted gamma-lactones, carrying a triple bond in the side chain. Lindlar-hydrogenation of the latter yielded the target compounds. (c) 2006 Elsevier Ltd. All rights reserved.