The thermolysis of (2-methoxyphenyl)methyltitanocene (2) in the presen
ce of various unsaturated substrates regioselectively to yield metalla
cycles, presumably via the intermediacy of the titanocene-benzyne comp
lex 3, is described. If the thermolysis is effected in the presence of
trimethylphosphine, the titanocene-benzyne complex Cp2Ti(eta2-C6H4-2-
OMe)(PMe3) (1a) can be isolated. The reactions of 1a and 3 are compare
d to those of the analogous zirconium complexes.