A novel lutidine‐based manganese PNP‐pincer complex has been synthesized for the selective N‐methylation of aromatic amines with methanol. Using borrowing hydrogen methodology, a selection of differently functionalized aniline derivatives is selectively methylated in good yields.
Conversion of amides to esters by the nickel-catalysed activation of amide C–N bonds
作者:Liana Hie、Noah F. Fine Nathel、Tejas K. Shah、Emma L. Baker、Xin Hong、Yun-Fang Yang、Peng Liu、K. N. Houk、Neil K. Garg
DOI:10.1038/nature14615
日期:2015.8
Although enzymes are able to cleave amide bonds in nature, it is difficult to selectively break the carbonânitrogen bond of an amide using synthetic chemistry; now the activation and cleavage of these bonds using nickel catalysts is used to convert amides to esters. Although enzymes are able to cleave amide bonds in nature, it is difficult to selectively break the carbonânitrogen bond of an amide using synthetic chemistry. In this paper the authors demonstrate that amide CâN bonds can be activated and cleaved using nickel catalysts. They used this methodology to convert amides to esters, which is a challenging and underdeveloped transformation. Amides are common functional groups that have been studied for more than a century1. They are the key building blocks of proteins and are present in a broad range of other natural and synthetic compounds. Amides are known to be poor electrophiles, which is typically attributed to the resonance stability of the amide bond1,2. Although amides can readily be cleaved by enzymes such as proteases3, it is difficult to selectively break the carbonânitrogen bond of an amide using synthetic chemistry. Here we demonstrate that amide carbonânitrogen bonds can be activated and cleaved using nickel catalysts. We use this methodology to convert amides to esters, which is a challenging and underdeveloped transformation. The reaction methodology proceeds under exceptionally mild reaction conditions, and avoids the use of a large excess of an alcohol nucleophile. Density functional theory calculations provide insight into the thermodynamics and catalytic cycle of the amide-to-ester transformation. Our results provide a way to harness amide functional groups as synthetic building blocks and are expected to lead to the further use of amides in the construction of carbonâheteroatom or carbonâcarbon bonds using non-precious-metal catalysis.
Deprotection of amides is a virtually universal transformation in organic synthesis, often employing traditional active reductants such as SmI2, hydrosilanes, hydroboranes or H2 under high-pressure. Herein, we describe a green and sustainable electrocatalytic hydrolysis of amides utilizing water as the hydrogen source, thereby ideally avoiding the use of high-pressure and flammable hydrogen gas or