Transition metal complexes diphosphine syntheses

Synthesis of chiral atropisomeric diphosphine type ligands is a current challenge in chemical research because their late transition metal complexes usually provide high enantioselectivity in homogenous catalytic reactions. [28] In practical point of view, preparation and optical resolution of racemic diphosphine oxides followed by the reduction of the separated enantiomers are usually more advantageous than an expensive enantioselective synthesis of one diphosphine enantiomer. [29]... 

Synthesis, characterization and applications in asymmetric catalysis of biheteroaromatic diphosphines and their transition metal complexes 04CCR(248)2151. 

A good example of enantioselective synthesis using catalysts is the hydrogenation of various alkenes, employing soluble transition metal complexes derived from optically active phosphines. For example (-h)-(2i ,3i )-2,3-butanediol can be converted to a diphosphine ligand. A variety of other such phosphines have been... 

The first transition metal catalysis using BINAP-ruthenium complex in homogeneous phase for enantioselective hydrogenation of P-ketoesters was developed by Noyori and co-workers [31]. Genet and co-workers described a general synthesis of chiral diphosphine ruthenium(II) catalysts from commercially available (COD)Ru(2-methylallyl)2 [32]. These complexes preformed or prepared in situ have been found to be very efficient homogeneous catalysts for asymmetric hydrogenation of various substrates such as P-ketoesters at atmospheric pressure and at room temperature [33]. 

Nuzzo, R.G., Haynie, S.L., Wilson, M.L. and Whitesides, G.M. (1981) Synthesis of functional chelating diphosphines and the use of these materials in the preparation of water soluble diphosphine complexes of transition metals. /. Org. Chem., 46, 2861-2867. 

In 1968, Knowles at Monsanto Company showed that a chiral transition metal based catalyst could transfer chirality to a nonchiral substrate resulting in a chiral product with one of the enantiomers in excess. The aim of Knowles was to develop an industrial synthesis process for the rare amino acid l-DOPA, which had proved useful in the treatment of Parkinson s disease. Knowles and co-workers at Monsanto discovered that a cationic rhodium complex containing DiPAMP (Fig. 2.5A), a chelating diphosphine with... 

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