Bond-Weakening Catalysis: Conjugate Aminations Enabled by the Soft Homolysis of Strong N–H Bonds
摘要:
The ability of redox-active metal centers to weaken the bonds in associated ligands is well precedented, but has rarely been utilized as a mechanism of substrate activation in catalysis. Here we,describe a catalytic bond-weakening protocol for conjugate amination wherein the strong N-H bonds in N-aryl amides (N-H bond dissociation free energies similar to 100 kcal/mol) are destabilized by similar to 33 kcal/mol upon by coordination to a reducing titanocene complex, enabling their abstraction by the weak H-atom acceptor TEMPO through a proton-coupled electron transfer process. Significantly, this soft homolysis mechanism provides a method to generate closed-shell, metalated nucleophiles under neutral conditions in the absence of a Bronsted base.
Silver-catalyzed cascade cyclization and functionalization of <i>N</i>-aryl-4-pentenamides: an efficient route to γ-lactam-substituted quinone derivatives
作者:Zeguo Fang、Lin Xie、Liang Wang、Qian Zhang、Dong Li
DOI:10.1039/d2ra05283k
日期:——
synthesis of γ-lactam-substituted quinone derivativesthrough a Ag2O-catalyzed cascade cyclization and functionalization of N-aryl-4-pentenamides has been developed. Related 2-oxazolidinone substituted quinone products can be also obtained with N-aryl allyl carbamates. The reactions proceed through an amidyl radical-initiated 5-exo-trig cyclization and followed radical addition to quinones. They provide an