A new aspect of magnesium bromide-promoted enantioselective aryl additions of triaryl(tetrahydrofuran)aluminum to ketones catalyzed by a titanium(IV) catalyst of trans-1,2-bis(hydroxycamphorsulfonylamino)cyclohexane

A novel aspect of MgBr2-promoted asymmetric triarylaluminum-tetrahydrofuran [AlAr3 (THF)] additions to ketones catalyzed by a titanium catalyst of 20 mol% trans-1,2-bis(hydroxycamphor-sulfonylamino)cyclohexane (2) is reported. The catalytic system works excellently for aromatic ketones with either an electron-withdrawing or an electron-donating substituent on the aromatic ring at the 2'-, 3'-, or 4'-positions, affording tertiary alcohols in excellent enantioselectivities of >= 90% ee, except for the cases of phenyl addition to 2'-methoxyacetophenone and 4-trimethylsilylphenyl (4-TMSC6H4) addition to acetopheneone.