Copper‐Catalyzed C(sp³)−H Amidation: Sterically Driven Primary and Secondary C−H Site‐Selectivity

Abstract

Undirected C(sp 3 ) À Hf unctionalization reactions often follow site-selectivity patterns that mirror the corresponding CÀHbond dissociation energies (BDEs). This often results in the functionalization of weaker tertiary CÀHb onds in the presence of stronger secondary and primary bonds.A n important, contemporary challenge is the development of catalyst systems capable of selectively functionalizing stronger primary and secondary CÀHbonds over tertiary and benzylic CÀHsites.Herein, we report aCucatalyst that exhibits ahigh degree of primary and secondary over tertiary CÀHb ond selectivity in the amidation of linear and cyclic hydrocarbons with aroyl azides ArC(O)N 3 .M echanistic and DFT studies indicate that C À Ha midation involves H-atom abstraction from R-H substrates by nitrene intermediates [Cu](k 2 -N,O-NC(O)Ar) to provide carbon-based radicals RC and copper-(II)amide intermediates [Cu II ]-NHC(O)Ar that subsequently capture radicals RC to form products R-NHC(O)Ar.T hese studies reveal important catalyst features required to achieve primary and secondary C À Ha midation selectivity in the absence of directing groups.

Terminal Imido Complexes of the Groups 9–11: Electronic Structure and Developments in the Last Decade

“…Acylimido complex 51 does not require directing groups for high regioselectivity in C−H amination catalysis. The sterically demanding β ‐diketiminato ligand (with ortho ‐diphenylmethyl and para ‐ tert‐ butyl substituents) leads to preferential activation of the stronger, yet more exposed, primary or secondary C−H bonds in comparison to the weaker, yet less accessible tertiary C−H bonds [104] …”

Copper(II)-Photocatalyzed N–H Alkylation with Alkanes

“…Examples include the coupling of nitrogen nucleophiles with alkyl halides, 2 reductive amination, 3 olefin hydroamination, 4 and nitrene insertion. 5 Copper catalysis Scheme 1. Nitrogen Nucleophile Alkylation Using Copper Peroxide Systems provides an alternative approach for the construction of C−N bonds.…”

RuV‐Acylimido Intermediate in [RuIV(Por)Cl2]‐Catalyzed C–N Bond Formation: Spectroscopic Characterization, Reactivity, and Catalytic Reactions

“…In 2000, we reported C−H amination of ethylbenzene by, e.g., Ru III (Me 3 tacn)/H 2 NCOPh [6, 7] . Recently, there is a surge of interest in C−H amination with acyl azides N 3 COR ( 1 ), dioxazolones, [8] H 2 NCOCF 3 , or N ‐substituted amides H(R′O)NCOR, as reported by Chang and others [9, 10, 12–15] employing directing group (DG) strategy (for intermolecular reactions) and by Warren and co‐workers [11] using Cu I (diketiminate)/N 3 COR for hydrocarbons without DGs. These reactions proceed via proposed M(NCOR) intermediates (Figure 1 aA, M=Fe, [5, 9] Co, [10] Cu, [7a, 11] Ru, [6, 12] Rh, [13, 14] Ir, [8, 13c, 15] Au [7b] ).…”

“… a) Literature examples: A) metal‐catalyzed acylnitrene transfer reactions via proposed M(NCOR) intermediates, [5–15] B) proposed Ru V (O) intermediates in [Ru IV (Por)Cl 2 ]‐catalyzed oxygen atom transfer reactions [20] . b) Ru V (NCOR) active intermediates in this work, evidenced by experimental studies, including ESI‐MS and EPR measurements and DFT calculations, in [Ru IV (Por)Cl 2 ]‐catalyzed acylnitrene transfer reactions.…”