Tandem dienyne cross-metathesis/ring-closing metathesis

Tandem enyne cross-metathesis/ring-closing metathesis between terminal alkynes and 1,5-hexadiene has been demonstrated using the 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium benzylidene complex. Synthesis of 2-substituted 1,3-cyclohexadienes using this one step tandem reaction is reported. In addition, metathesis products were subjected to [4+2] cycloaddition with N-methylmaleimide yielding the corresponding cycloadducts in one synthetic step.