Metathesis and Metallotropy:  A Versatile Combination for the Synthesis of Oligoenynes

We have demonstrated that the combined use of enyne metathesis and metallotropic [1,3]-shift of the corresponding alkynyl ruthenium carbenes is a powerful synthetic tool to construct oligoenynes. In this reaction, alkynyl carbene intermediates formed from an initial ring-closing metathesis reaction (RCM) undergo repetitive [1,3]-shifts and RCMs to give the final products. Linear poly-1,3-diynes containing repeating functionality of the type -[XCH2CCCCCH2]n- generated long-chain conjugated oligoenynes up to n = 5.