SYNTHESIS OF ETA(3)-2-STANNYLMETHYLALLYLPALLADIUM COMPLEXES AND THEIRDESTANNYLATION LEADING TO TRIMETHYLENEMETHANE-PALLADIUM SPECIES

eta(3)-2-Stannylmethylallylpalladium chloride dimer [Pd(eta(3)-CH2C(CH (2)SnMe(3))CH2)Cl](2) (1a) reacted with a neutral ligand L to form cor responding cationic complexes [Pd(eta(3)-CH2C(CH(2)SnMe(3))CH2)L(2)]Cl (L = PPh(3): 2a, 1/2 bipy: 5 (bipy = 2,2'-bipyridyl)), which were cha racterized by H-1 NMR at low temperature only for 2a and at room tempe rature for 5. On addition of Bu(3)SnCl the cationic complex 5 underwen t stannyl group exchange equilibrium with [Pd(eta(3)-CH2C(CH(2)SnBu(3) )CH2) (bipy)]Cl. Addition of 2 equiv PPh(3) and RCHO (R = Ph, CH2 = CH ) to la at room temperature afforded the cycloaddition products, methy lenetetrahydro- furans, in good yields. The complex 1a reacted with Ph CHO in the presence of bipy and dppe (dppe = 1,2 bis(diphenylphosphino )ethane) to give the aldehyde adduct complexes [Pd(eta(3)-CH2C(CH(2)CH Ph(OSnMe(3)))CH2)L(2)]Cl (L = 1/2 bipy, 1/2 dppe), which were characte rized by H-1 NMR. The possible generation and the reactivities of the trimethylenemethane-palladium complex intermediate are discussed in th e light of these results.