Addition of a beta C-H bond in conjugate enones to internal acetylenes to give conjugate dienones proceeded with the aid of RuH2(CO)(PPh3)(3) as the catalyst. The reaction of pivaloylcyclohexene with diphenylacetylene gave the corresponding dienone in high yield. Acylpyranes can also be used in these olefinic C-H/acetylene coupling reactions. Phenyltrimethylsilylacetylene is also able to serve as a C-H bond acceptor. (C) 2002 Elsevier Science B.V. All rights reserved.