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 PhC CMe 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 (PhC CMe, PhC CPh) than for terminal alkynes (HC CPh, HC CtBu, HC CCO2Me) ...
[Efremov, Dimitry A.; Zavlin, Pavel M.; Essentseva, Nataly S.; Tebby, John C. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1994 , # 21 p. 3163 - 3168]