| Abstract |
Trans-[PdCl2L2] (1, L = 3-NNMe2C10H14O), under mild reaction conditions, acts as a catalyst for the cyclic trimerization of alkynes. The best performance is achieved for the reaction with PhCequivalent toCMe that affords 1,3,5-trimethyl-2,4,6-triphenyl benzene with high activity and selectivity (ca. 99\%). As a general trend the catalytic activity is higher for internal (PhCequivalent toCMe, PhCequivalent toCPh) than for terminal alkynes (HCequivalent toCPh, HCequivalent toC Bu, HCequivalent toCCO(2)Me). Under more drastic experimental conditions the reaction of 1 with PhCequivalent toCPh yields trans-[PdCl2(PhCequivalent toCPh)(2)] and no catalytic activity is observed. The molecular structure of 1,3,5-trimethyl-2,4,6-triphenyl benzene was confirmed by X-ray diffraction analysis. The molecules were characterized by H-1- and C-13-NMR spectroscopies, FAB-MS and, in some cases, elemental analyses. (C) 2003 Elsevier B.V. All rights reserved. |
