Pd-CATALYZED SYNTHESIS OF (5 <I>E</I>)-TETRADEC-5-EN-7-YN-2-ONE
A stereodirected synthesis of (5 E )-tetradec-5-en-7-yn-2-one, precursor of a number of low-molecular bioregulators based on the industrially available ( E )-1,3-dichloropropene was developed. Alkylation of acetoacetic ester by ( E )-1,3-dichloropropene under phase-transfer catalysis conditions afforded in good yield ethyl(4 E )-2-acetyl-5-chloropent-4-enoate. Its subsequent decarbethoxylation results in the formation of (5 E )-chlorohex-5-en-2-one. The cross-coupling of derived ketone with 1-octyne proceeds in the presence of weakly ligated complex PdCl 2( i -PrCN) 2 and CuI in piperidine to produce corresponding (5 E )-tetradec-5-en-7-yn-2-one in a high yield (90%).