Alkyne cross metathesis reactions of extended scope

[GRAPHICS] A catalyst formed in situ from Mo[N(t-Bu)(Ar)](3) 1 (Ar = 3,5-dimethylphenyl) and CH2Cl2 in toluene effects cross metathesis reactions of functionalized alkynes that are beyond reach of more traditional promoters. An application to the synthesis of prostaglandin E-2 (PGE(2)) 19 and the acetylated PGE derivative 18b shows the compatibility of this method with sensitive substrates.