Nickel‐Catalyzed Decarbonylative Borylation of Amides: Evidence for Acyl C−N Bond Activation

Abstract

A nickel/N-heterocyclic carbene catalytic system has been established for decarbonylative borylation of amides with B2 nep2 by C-N bond activation. This transformation shows good functional-group compatibility and can serve as a powerful synthetic tool for late-stage borylation of amide groups in complex compounds. More importantly, as a key intermediate, the structure of an acyl nickel complex was first confirmed by X-ray analysis. Furthermore, the decarbonylative process was also observed. These findings confirm the key mechanistic features of the acyl C-N bond activation process.

N‐Boc‐Amides in Cross‐Coupling Reactions

“…Decarbonylative processes can also be employed to form the C−B bond. Thus, Shi and co‐workers published excellent results on the formation of arylboronic esters starting from N ‐Boc‐benzamides . They employed a nickel/NHC catalytic system, which can insert into the amidic C−N bond to provide an acyl–nickel(II) complex.…”

Mild Ring‐Opening 1,3‐Hydroborations of Non‐Activated Cyclopropanes

“…Substrates containing spiro cyclopropanes with an indane or tetralin scaffold (2b,c)w ere all rapidly ring-opened, and the corresponding pinacol boronate esters were isolated in excellent yields.H alogen substituents (F,C l, Br and I) worked well under the reaction conditions (2d-h), highlighting the potential of this process in combination with further conventional cross-coupling transformations.W hile the O-demethylation process with BBr 3 is well documented, substrate 1i bearing am ethoxy group is compatible with this process,a ffording desired product 2i in 55 %y ield. [21] Having established optimal reaction conditions,w ef ound that the 1,3-hydroboration of cyclopropane gas (3)u nder the pressure generated by aballoon could produce n PrBpin (4)in71%yield (Scheme 1). Boronates 2k and 2l were obtained in good yields from 1,1-arylalkylcyclopropanes after the ringopening reactions.1,1-Dialkylcyclopropanes 1m-o could also be subjected to our reaction conditions and desired products 2m-o were obtained in good yields after the ring-openinghydroboration reaction.…”

Kinetic Modeling of the Nickel-Catalyzed Esterification of Amides

“…The reaction that we chose to pursue is the nickel-catalyzed conversion of amides to esters, which represents a unique and challenging transformation. 4−9 An example of this reaction is depicted in Figure 2, wherein benzamide 1 is coupled with (−)-menthol ( 2 ) to furnish ester 3 in 88% yield. Notably, this reaction proceeds at 80 °C using both 10 mol % Ni(cod) 2 and 10 mol % SIPr in toluene (0.66 M).…”