We report a Chan–Lam coupling reaction of benzylic and allylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition-metal-mediated transformation of a tertiary alkylboron reagent. Initial investigation into the reaction mechanism suggests that transmetalation from B to Cu occurs through a single-electron, rather than a two-electron process.
The Cu-catalysed coupling of arylboronic acids with amines, known as the Chan-Lam reaction, is used widely to prepare aryl amines. In contrast, alkyl variants of this reaction, while highly desirable, are underdeveloped. Herein, we report a Chan-Lam coupling reaction of benzylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition metal-mediated transformation of a tertiary alkylboron reagent. The method is operationally simple and tolerates a broad range of functional groups. Initial investigation into the reaction mechanism suggests that transmetallation from B to Cu occurs through a single electron, rather than a two-electron process.
The Cu-catalysed coupling of arylboronic acids with amines, known as the Chan-Lam reaction, is used widely to prepare aryl amines. In contrast, alkyl variants of this reaction, while highly desirable, are underdeveloped. Herein, we report a Chan-Lam coupling reaction of benzylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition metal-mediated transformation of a tertiary alkylboron reagent. The method is operationally simple and tolerates a broad range of functional groups. Initial investigation into the reaction mechanism suggests that transmetallation from B to Cu occurs through a single electron, rather than a two-electron process.
A nickel catalyst for the allylboration of aldehydes is reported, facilitating the preparation of homoallylic alcohols in high diastereoselectivity. The observed diastereoselectivities and NMR experiments suggest that allylation occurs through a well-defined six-membered transition state, with nickel acting as a Lewis acid.
We report a Cu-catalysed oxidative coupling of aliphatic amines with alkylboronic esters to give high value alkyl amines, products found widely in applications from medicinal chemistry to materials science. This operationally simple reaction, which can be performed on gram scale, runs under mild conditions and exhibits excellent functional group tolerance. The terminal oxidant of the reaction is O2 from the air, avoiding the need for additional chemical oxidants. Investigation into the reaction mechanism suggests the intermediacy of an alkyl radical, generated from the boronic ester upon activation through an amino radical transfer process. To demonstrate its utility and potential for late-stage functionalization, we showcase the method as the final step in the total synthesis of a TRPV 1 antagonist.
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