The site selectivity of electrophilic palladation has been studied by using two bis(aminomethyl)-substituted benzenes 1,3-(Me 2 NCH 2) 2 C 6 H 4 (6) and 2,6-(Me 2 NCH 2) 2 C 6 H 3 (SiMe 3) (7) and Li 2 [PdCl 4 ] or Pd(OAc) 2 in solution in MeOH or CH 2 Cl 2. The major product of direct palladation of 6 in both solvents is the polymeric cyclopalladated organometallic complex [1,5-{PdCl} 2-2,4-(Me 2-NCH 2) 2 C 6 H 2 ] n , which was characterized as its dinuclear pyridine derivative [1,5-{PdCl(C 5 H 5 N)} 2-2,4-(Me 2 NCH 2) 2 C 6 H 2 ] (9). The effect of the trimethylsilyl group present at the 1-position in 7 leads to inversion of the site selectivity in comparison to that observed for 6, and to activation of the C ± Si bond when MeOH is used as solvent; the major product of this direct palladation is the known monomeric cyclopalladated complex [{PdCl}2,6-(Me 2 NCH 2) 2 C 6 H 3 ] (8). However, using CH 2 Cl 2 instead of MeOH in the palladation reaction of 7 leads to the major product arising from C ± H rather than C ± Si bond activation.

No abstract

The site selectivity of electrophilic palladation has been studied by using two bis(aminomethyl)-substituted benzenes 1,3-(Me 2 NCH 2 ) 2 C 6 H 4 (6) and 2,6-(Me 2 NCH 2 ) 2 C 6 H 3 (SiMe 3 ) (7) and Li 2 [PdCl 4 ] or Pd(OAc) 2 in solution in MeOH or CH 2 Cl 2 . The major product of direct palladation of 6 in both solvents is the polymeric cyclopalladated organometallic complex [1,5-{PdCl} 2 -2,4-(Me 2 -NCH 2 ) 2 C 6 H 2 ] n , which was characterized as its dinuclear pyridine derivative [1,5-{PdCl(C 5 H 5 N)} 2 -2,4-(Me 2 NCH 2 ) 2 C 6 H 2 ] (9). The effect of the trimethylsilyl group present at the 1-position in 7 leads to inversion of the site selectivity in comparison to that observed for 6, and to activation of the C ± Si bond when MeOH is used as solvent; the major product of this direct palladation is the known monomeric cyclopalladated complex [{PdCl}2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ] (8). However, using CH 2 Cl 2 instead of MeOH in the palladation reaction of 7 leads to the major product arising from C ± H rather than C ± Si bond activation.