Catalytic CH Amination with Unactivated Amines through Copper(II) Amides

Abstract

En route to catalysis: Two equivalents of the three‐coordinate copper(II) amide [(Cl2NN)Cu]‐NHAd participate in stoichiometric CH amination by a H‐atom abstraction/radical capture sequence. This active species may be generated through a copper(II) tert‐butoxide intermediate to allow for the unprecedented catalytic amination of sp3‐CH bonds with unactivated alkylamines. This method greatly expands the range of amines for catalytic CH amination since most protocols require N‐based electron‐withdrawing groups.

A Stable Aminyl Radical Coordinated to Cobalt

“…In the past few years, examples of metal complexes with aminyl (CNR 2 ), nitrene radical/imidyl (CNR), and nitridyl radical ligands( CN) have been isolated, and despite their intrinsic high reactivity,t hey have demonstrated high selectivity in certain catalytic processes. [32] Here, we report the first stable aminyl radical complex of cobalt.Ac omparison of its spectroscopic properties, electrochemical behavior, spin density,structuralfeatures, and reactivity with respect to the heavier Rh and Ir analogues is made. [7] Related and catalytically relevant imidyl/nitrene radical complexes of cobalt porphyrins (B)w ere characterized in detail by de Bruin and co-workersu sing av ariety of spectroscopic (EPR, X-ray absorption, UV/Vis, IR), compu- [7,8,15] nitridyl( D), [16] and aminyl (E-M) [21][22][23][24][25][26][27][28][29][30][31] radicalc omplexes.…”

The Persistent Radical Effect in Organic Synthesis

“…[292] Calculations supported the suggested combination of the alkyl radical with the amine ligand, which is referred to as "radical capture"a nd can be considered as aformal homolytic substitution at nitrogen. [290] Based on this seminal work, other radical Cu-catalyzed CÀN bond formations at activated CÀHs ites with amides,s ulfonamides,i mides, [293] carbamates, [294] sulfoximines, [295] and Weinreb amides [296] as the nucleophilic Nsources have been developed. Recently,c arboxylic acids in combination with alkyl chlorides [297] and hypervalent iodine [298] were established in such couplings.M oreover,s uch aminations can be combined with ar adical addition to aC =Cd ouble bond where uncatalyzed radical C À Cb ond formation precedes the Cucatalyzed C À Nbond formation.…”

“…[301] Depending on the ligands at the Cu I complex, it was proposed that aryl radicals are generated either by iodine atom transfer or reductive cleavage of the C À Ibond in the starting aryl iodides. In analogy to the mechanism suggested by Warren, [290,291] the aryl radical directly adds to the nitrogen atom of the intermediate Cu II amine complex to deliver the targeted product and the starting Cu I complex. [290] c) Asymmetric cyanation and arylation by radical-metalc rossover reactions.…”

Tuning steric and electronic effects in transition-metal β-diketiminate complexes

“…As a result, dimeric/polymeric metal complexes are more often formed with less sterically hindered β-diketiminate ligands. For example, comparisons with more hindered monomeric analogues were reported for [LScCl 2 ] n (L tBu,iPr , 16 n=1; L Me,iPr , 17 n=2), [LSc(CH 3 ) 2 ] n (L tBu,iPr , 16 n=1; L Me,iPr , 17 n=2), [LFeCl] n (L tBu,iPr , 18 n=1; L Me,iPr , 19 Me L Me,Me , 20 n=2), [LFeF] n (L tBu,iPr , n=1; L Me,iPr , n=2), 21 [LCoCl] n (L tBu,iPr , 22 n=1; L Me,iPr , 23 n=2), [LNiCl] n (L tBu,iPr , 22 n=1; L Me,iPr , 24 L Me,Me , 25 n=2), [LNi(CO)] n , (L tBu,iPr , 26 L Me,iPr , 27 n=1; L Me,Me , 28 n=2), [L R,iPr CuCl] n (L Me,iPr , 29 Cl L Me,iPr , 29 n=1; Ph L H,iPr , 30 L Me,Cl , 31 n=2), and [LPd(μ-OAc)] n (L Me,iPr , 32 n=1; L Me,H 32 Cl L Me,H , 33 n=2). The angle between the two β-diketiminate ligand planes in dimeric metal complexes is often influenced by the different substituents on the ligand (Table 3.1.1).…”