Camphorsulfonamide enantioselective additions

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... 

Chiral Zn(salen) catalyzed enantioselective alkynylation of ketones has been examined by Cozzi82 and by Saito and Katsuki83. Camphorsulfonamide/Cu(OTf)284, Ti(0-i-Pr)4/BINOL85 and Et3Al/cinchona alkaloid86 systems have also been reported. Chiral / -amino alcohols work as chiral catalysts without an additional Lewis acid component87. 

Alkynylation of Ketones. By combining catalytic amounts of copper(II) trifiate and camphorsulfonamides an effective chiral catalyst system is produced, which is effective in the production of tertiary propargyUc alcohols, with good to excellent enantioselectivities. These reactions represent a highly enan-tioselective catalytic addition of afkynyl zinc reagents to simple ketones (eq 43). 

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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