Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2011 Oct 5;133(39):15362-4. doi: 10.1021/ja2079515. Epub 2011 Sep 13.
With the aid of a chiral nickel catalyst, enantioselective γ- (and δ-) alkylations of carbonyl compounds can be achieved through the coupling of γ-haloamides with alkylboranes. In addition to primary alkyl nucleophiles, for the first time for an asymmetric cross-coupling of an unactivated alkyl electrophile, an arylmetal, a boronate ester, and a secondary (cyclopropyl) alkylmetal compound are shown to couple with significant enantioselectivity. A mechanistic study indicates that cleavage of the carbon-halogen bond of the electrophile is irreversible under the conditions for asymmetric carbon-carbon bond formation.
在手性镍催化剂的辅助下，通过γ-卤代酰胺与烷基硼试剂的偶联，可以实现羰基化合物的对映选择性γ-（和 δ-）烷基化。除了一级烷基亲核试剂外，首次实现了对未活化的烷基亲电试剂、芳基金属试剂、硼酸酯和二级（环丙基）烷基金属化合物的不对称交叉偶联，具有显著的对映选择性。一项机理研究表明，在不对称碳-碳键形成的条件下，亲电试剂的碳-卤键的断裂是不可逆的。
