Bidentates nitrogen-oxygen ligands

BIDENTATE NITROGEN-OXYGEN LIGANDS 20.4.2.1 N—O Bidentates with Amine Group Donors... 

A great nnmber of chiral bidentate nitrogen and oxygen ligands, which served well with other cations than lithinm, are known . Only very limited success was achieved with organolithium compounds in the classical examples of addition reactions onto aldehydes 335-337... 

Complexes with bidentate ligands having sulfur-nitrogen, oxygen-sulfur or oxygen-nitrogen donor... 

Some complexes which satisfy this definition are dealt with elsewhere, however. Those with X or Y as the Group V donors P, As or Sb are dealt with in Chapter 14 of this volume. Those with X or Y = Hg are described in Chapter 11 and the Group IV donors Si, Ge, Sn and Pb are included in Chapter 12.2, With very few exceptions this means that the relevant X,Y combinations are pairs derived from nitrogen, oxygen, sulfur or selenium donor groups. However, some specific examples of these combinations also occur elsewhere in this work. Amino acids (generally N—O bidentates) are covered in Chapter 20.2, Schiff base ligands (N—O or N—S) in Chapter 20.1, and several S—O... 

The advances that have taken place over the past five years in catalytic, enantioselective aldol addition reactions is evident in a number of important respects. The types of transition metals and their complexes that function competently as catalysts have been expanded considerably. Thus, in addition to B(III), Ag(I), Au(I), Sn(II), and La(III), chiral catalysts prepared from Cu(II), Ti(IV), Ln(III), Si(IV), Pt(II) and Pd(II) have been introduced. The expansion in the use of transition metals has taken place hand-in-hand with the design and synthesis of new bidentate and tridentate organic ligands based on nitrogen, oxygen, and phosphorus donors. Additionally, whereas the older methods primarily relied on the use of Lewis-acids for the activation of... 

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