ABSTRACT
The involvement of manganese radical for halogen atom transfer (XAT) reactions has been esteemed as one reliable method but encountered with limited catalytic models. In this paper, a novel bimetallic relay catalysis of Mn2 (CO)10 and cobaloxime has been developed for divergent dehydrogenative difluoroalkylation of alkenes using commercially available difluoroalkyl bromides. A wide range of structurally diverse terminal, cyclic and internal alkenes as well as tetrasubstituted alkenes are found to be good coupling partners to deliver difluoroalkylated allylic products and difluoromethylated cyclic products, accompanied with the production of H2 as the by-product. This bimetallic relay strategy features broad substrate scope, mild reaction conditions and excellent functional group compatibility. Its success represents an important step-forward to expedite the construction of a rich library of difluoroalkylated products.
ABSTRACT
Aromatic tertiary amines are one of the most important classes of organic compounds in organic chemistry and drug discovery. It is difficult to efficiently construct tertiary amines from primary amines via classical nucleophilic substitution due to consecutive overalkylation. In this paper, we have developed a radical tandem C-N coupling strategy to efficiently construct aromatic tertiary amines from commercially available carboxylic acids and nitroarenes. A variety of aromatic tertiary amines can be furnished in good yields (up to 98%) with excellent functional group compatibility under mild reaction conditions. The use of two different carboxylic acids also allows for the concise synthesis of nonsymmetric aromatic tertiary amines in satisfactory yields. Mechanistic studies suggest the intermediacy of the arylamine-(TPP)Fe(III) species and might provide a possible evidence for an SH2 (bimolecular homolytic substitution) pathway in the critical C-N bond formation step.
Subject(s)
Amines , Ferric Compounds , Amines/chemistry , Carboxylic Acids/chemistry , CatalysisABSTRACT
In this communication, we report a photocatalyzed amidation strategy from carboxylic acids and tertiary amines through C-N bond cleavage. A wide scope of structurally diverse carboxylic acids participate smoothly in the reaction, providing the desired tertiary amides with moderate-to-good yields (34 examples, up to 93% yield). This amidation strategy provides an alternative way to address the regioselectivity between nucleophilic functional groups, thus complementing the functional group compatibility of classical amidation protocols. Its synthetic robustness is also proved by the late-stage modification of several complex molecules and gram-scale applications.
