Camphorsulfonamide ligands

Scheme 3.48 C2-S5mmetric bis(camphorsulfonamides) ligands for addition of ZnEt2 to benzaldehyde.

In the same area, Moreau et al. have developed new hydrophobic ionic liquids containing chiral camphorsulfonamide units and showed that they could be used as ligands for the Ti-catalysed addition of ZnEt2 to benzaldehyde. The ionic... 

On the other hand, in the presence of Lewis acid, addition of dialkylzinc to ketones occurs (equation 14)45. A stoichiometric amount of Ti(OPr-i)4 and a catalytic amount of camphorsulfonamide 33 enable an enantioselective addition of dialkylzincs to ketones46. Later, bis(sulfonamide) ligand 34 was found to be a more enantioselective catalyst in this... 

Compared to the well-developed organozinc addition to aldehydes, the related addition to ketones has been far less studied. However, the first catalytic addition of diaUcylzinc to ketones has been achieved few years ago using camphorsulfonamide alcohols ligands and Ti(0-(-Pr)4 salt (equation 66). In the same year, it was also discovered that 15 mol % of (-l-)-DAIB catalyze the diphenylzinc addition to ketones to generate chiral (see Chiral) tertiary alcohols with up to 91% e.e. (equation 67). 

Most of the efforts in this area centered on the synthesis of bis-camphorsulfonamides from either a chiral or an achiral diamine scaffold. The optimum derivative was found to be 44, which proved to be an excellent ligand for the Ti(O Pr)4-catalyzed addition of Et2Zn to ketones (eq 18). ... 

The addition of phenylacetylene to aromatic ketones gave the corresponding tertiary propargylic alcohols. The best enantioselectivity (97% ee) was obtained in alkynylation of 2-chloroacetophenone in the presence of a camphorsulfonamide-based chiral ligand (13). 

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