A new cross-coupling reaction has been developed for the introduction of an alkyne moiety to an anisole derivative through C-O bond activation using an NHC ligand. This method has been used for direct alkynylation of a broad range of anisole derivatives and provided rapid access to compounds with potential applications in biological and materials science.
We report nickel-catalyzed cross-coupling of methoxyarenes with alkylmagnesium halides, in which a methoxy group is eliminated. A wide range of alkyl groups, including those bearing β-hydrogens, can be introduced directly at the ipso position of anisole derivatives. We demonstrate that the robustness of a methoxy group allows this alkylation protocol to be used to synthesize elaborate molecules by combining it with traditional cross-coupling reactions or oxidative transformation. The success of this method is dependent on the use of alkylmagnesium iodides, but not chlorides or bromides, which highlights the importance of the halide used in developing catalytic reactions using Grignard reagents.
Nickel-catalyzed cross-coupling of methoxyarenes with alkyl Grignard reagents, which involves the cleavage of the C(aryl)-OMe bond, has been developed. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand allows the introduction of a variety of alkyl groups, including Me, Me3SiCH2, ArCH2, adamantyl, and cyclopropyl. The method can also be used for the alkylative elaboration of complex molecules bearing a C(aryl)-OMe bond.
Herein,
we describe a new catalytic approach to accessing aromatic
amines from an abundant feedstock, namely phenols. The most reliable
catalytic method for converting phenols to aromatic amines uses an
activating group, such as a trifluoromethane sulfonyl group. However,
this activating group is eliminated as a leaving group during the
amination process, resulting in significant waste. Our nickel-catalyzed
decarboxylation reaction of aryl carbamates forms aromatic amines
with carbon dioxide as the only byproduct. As this amination proceeds
in the absence of free amines, a range of functionalities, including
a formyl group, are compatible. A bisphosphine ligand immobilized
on a polystyrene support (PS-DPPBz) is key to the success of this
reaction, generating a catalytic species that is significantly more
active than simple nonsupported variants.
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