Science of Synthesis

Takacs, J. M.; Vayalakkada, S., Science of Synthesis, (2001) 1, 320.

The majority of the chemistry described in Section ‌1.2.4‌1.2.4, involves the formation of palladium(II)–alkene π-complexes in situ, as reactive intermediates. However, there are two general methods for the preparative synthesis of such complexes, namely, the direct reaction of palladium(II) chloride with an alkene and the displacement of weakly bound ligands (L) from PdX2L2 or M2Pd2Cl4.[‌1‌,‌2‌] The direct reaction of palladium(II) chloride with an alkene has found some use; e.g. [PdCl2(DMF)2] reacts with various substituted C-allylglycine derivatives to produce N,η2-alkenamine chelates such as ‌11‌ (‌Scheme 3‌).[‌3‌] However, it is generally less than satisfactory for preparative use since it is depends strongly on the nature of the PdX2L2 complex employed and is frequently accompanied by formation of η3-allylpalladium complexes. The displacement of weakly bound ligands from PdX2L2 or M2Pd2Cl4 has been used more extensively. For example, sodium tetrachloropalladate reacts with C-allyl-N-(diphenylmethylene)glycine to yield the alkene complex ‌12‌.[‌3‌] This example illustrates the potential for C—H insertion chemistry that can at times be observed.

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References