Tetrapodal phosphine ligand

Excellent yields have also been obtained using the tetrapodal phosphine ligand Tedicyp, in which four phosphi-nomethyl groups are attached to the same face of the cyclopentane ring. The couplings were performed in the presence of [(allyl)PdCl]2, Tedicyp, and 5% Cu(l) as co-catalyst <2005TL1717>. 

A new tetrapodal phosphine ligand, ds,ds,ds-l,2,3,4-tetrakis(diphenylphosphino-methyl)cyclopentane (Tedicyp), in association with [PdCl(C3H5)]2, is an extremely efficient catalyst for allylic amination [20]. Addition of diisopropylamine to an allyl acetate [Eq. (3)] is suprisingly higher in water than in THF. 

Bidentate phosphines such as DPPE, DPPP and DPPB play important roles in some reactions. Another bidentate phosphine is DPPF (XI-1), which is different from other bidentate phosphines, showing its own characteristic activity. The tetrapodal phosphine ligand, cw.cw.m-1,2,3,4-tetrakis(diphenylphosphinomethyl)-cyclopentane (Tedicyp) (X-1) was found to be a good ligand, and its Pd complex gives high turnover numbers [17]. 

Alternatively, a catalytic system consisting of the tetrapodal phosphine ligand Tedicyp 66 and the allylpalladium chloride dimer ([PdCl(C3H5)]2) can be used for efficient Heck vinylation reactions (Scheme 48, Table 26) [341]. The crosscoupling of 3,4-dibromothiophene 116 with various alkenes 117 gives rise to the corresponding vinylated products 118 and 119. 

Tedicyp-based system or with a simple phosphine-free system (entries 1 and 3) under otherwise almost identical conditions reveals a more or less matching performance. It seems very likely that tetrapodal phosphines serve as effective supporting ligands, thereby ensuring almost infinite stability of palladium(O) species. 

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