Synthesis of η3-2-stannylmethylallylpalladium complexes and their destannylation leading to trimethylenemethane-palladium species

Article abstract of DOI:10.1016/0022-328X(94)85004-6

η³-2-Stannylmethylallylpalladium chloride dimer 3-CH2C(CH2SnMe3)CH2)Cl>2 (1a) reacted with a neutral ligand L to form corresponding cationic complexes 3-CH2C(CH2SnMe3)CH2)L2>Cl (L=PPh3: 2a, 1/2 bipy: 5 (bipy=2,2'-bipyridyl)), which were characterized by 1H NMR at low temperature only for 2a and at room temperature for 5.On addition of Bu3SnCl the cationic complex 5 underwent stannyl group exchange equilibrium with 3-CH2C(CH2SnBu3)CH2) (bipy)>Cl.Addition of 2 equiv PPh3 and RCHO (R=Ph, CH2=CH) to 1a at room temperature afforded the cycloaddition products, methylenetetrahydrofurans, in good yields.The complex 1a reacted with PhCHO in the presence of bipy and dppe (dppe = 1,2-bis(diphenylphosphino)ethane) to give the aldehyde adduct complexes 3-CH2C(CH2CHPh(OSnMe3))CH2)L2>Cl (L=1/2 bipy, 1/2 dppe), which were characterized by 1H NMR.The possible generation and the reactivities of the trimethylenemethane-palladium complex intermediate are discussed in the light of these results.Key words: Palladium; Stannyl; Destannylation; Trimethylenemethane