Widely used as catalyst, in the presence of a phosphine ligand and a base, in the Heck (or Mizoroki-Heck) reaction, for coupling of aryl or vinyl halides with alkenes. Reviews: Org. React., 27, 345 (1982); Acc. Chem. Res., 12, 146 (1979); 28, 2 (1995); Angew. Chem. Int. Ed., 33, 2379 (1994); Chem. Rev., 100, 3009 (2000). In many reactions, e.g. the arylation of ɑ?-unsaturated esters, Tri(o-tolyl)-phosphine is superior to triphenylphosphine: J. Org. Chem., 43, 2952 (1978). o-Allylic or o-vinylic phenols undergo phosphine-free Pd-catalyzed cross-coupling with vinylic halides and triflates, giving dihydrobenzopyrans and dihydrobenzofurans respectively: Tetrahedron Lett., 39, 237 (1998). In the presence of TBAB, catalyzes direct homocoupling of aryl halides: Tetrahedron Lett., 39, 2559 (1998).
