trans-1-Sulfonylamino-2-isoborneolsulfonylaminocyclohexane Derivatives: Excellent Chiral Ligands for the Catalytic Enantioselective Addition of Organozinc Reagents to Ketones

The catalytic enantioselective addition of different organozinc reagents (such as alkyl and aryl derivatives or in situ generated aryl, allyl alkenyl, and alkynyl derivatives obtained through different transmetallation processes) to simple ketones has been accomplished by using titanium tetraisopropoxide and chiral ligands derived from substituted trans‐1‐sulfonylamino‐2‐isoborneolsulfonylaminocyclohexane, producing the corresponding tertiary alcohols with enantiomeric excesses (ee) up to >99 %. A simple and efficient procedure for the synthesis of the chiral ligands used in these reactions is described. Ligand design: The catalytic enantioselective synthesis of tertiary alcohols is a major challenge in synthetic organic chemistry. The reaction between poor electrophilic ketones and organozinc reagents catalyzed by ligands derived from isoborneolsulfonamides (see scheme) is presented as a possible answer to this challenge.