Selective synthesis of monoorganotin trihalides: the direct reaction of allylic halides with tin(II) halides catalyzed by platinum and palladium complexes

The reaction of 3-haloalkenes (3-chloropropene, 3-bromopropene, 3-chloro-2-methylpropene, 1-chloro-2-butene) with SnX2 (X=Cl, Br) to form mono-allyltin trihalides, was catalyzed by several platinum and palladium complexes of the type MZ2L (M=Pt, Pd; Z=Me, Cl; L=2,2′-bipyridine, 1,10-phenanthroline or dppe). The highest yield of allyltin trichloride was obtained for the reaction of 3-chloropropene with SnCl2 catalyzed by PdMe2(phen) (83%) while the yield obtained with the other catalysts decreased in the order PdCl2(phen), PdCl2(bipy)>PdMe2(bipy)>PtCl2(phen)>PtMe2(bipy)>PtMe2(phen)>PtCl2(bipy). Interestingly, PdCl2(PhCN)2 and Pd(PPh3)4 had no activity at all. The yield of allyltin trichloride was not only dependent on the activity of the catalyst but also on the decomposition rate of the product in the presence of the catalyst. 3-Bromopropene gave 19% of allyltin tribromide when reacted with SnBr2. The other 3-haloalkenes did react but the resulting monoallylictin trihalides were not stable enough to produce significant yields. Reaction of both, benzyl chloride and chlorobenzene, led to catalyst decomposition. In addition, SnCl2 catalyzed formation of polybenzyl was observed in the case of benzyl chloride.