Alkyne metathesis with simple catalyst systems: High yield dimerization ofpropynylated aromatics; Scope and limitations

High yield dimerization of propynylated benzenes and propynylnaphthalene by a mixture of Mo(CO)(6) and 4-chlorophenol at 140 degrees C in 1,2-dichloro benzene is reported to give the corresponding disubstituted alkynes. The sc ope and limitation of the reaction and the influence of substitution patter n and substitution type are discussed. Oxygen or nitrogen carrying substrat es metathesize in moderate to good yields and ortho-alkyl substituted examp les form the respective tolanes very efficiently. (C) 1999 Elsevier Science Ltd. All rights reserved.