μ-Oxo-Hypervalent-Iodine-Catalyzed Oxidative C–H Amination for Synthesis of Benzolactam Derivatives

Abstract

Benzolactams have unique biological activity and high utility in the synthesis of valuable compounds with direct applicability to oxindole alkaloids and antibacterial agents. Despite recent advances in organic chemistry and the growing number of reported methods for synthesizing benzolactams, their preparation still requires a multistep process. C-H amination reactions can convert aromatic C(sp 2 )-H bonds directly to C(sp 2 )-N bonds, and this direct approach to C-N bond formation offers effective access to benzolactams. Hypervalent iodine reagents are promising tools for achieving oxidative C-H amination. Motivated by our ongoing research efforts toward the development of useful hypervalent-iodine-mediated oxidative transformations, we herein describe an effective intramolecular oxidative C-H amination reaction based on -oxo hypervalent iodine catalysis for the synthesis of benzolactams bearing various functional groups.

Dehydrogenative Electrochemical Synthesis of N‐Aryl‐3,4‐Dihydroquinolin‐2‐ones by Iodine(III)‐Mediated Coupling Reaction

“…The mechanism regarding regiochemistry is supported by the literature. [14,16,17,49] Scheme 4. Grouping of the substrates according to their oxidation potential (top) and proposed mechanisms for each group (center, bottom).…”

“…Conventionally, the 1H-3,4-dihydroquinolin-2-one skeleton can be synthesized through intramolecular CÀ N bond formation either transition metal-catalyzed by Buchwald-Hartwig [12] or Goldberg [13] amination reactions (Scheme 1, a), or by iodine(III)promoted transformations, applying stoichiometric amounts of the hypervalent iodine(III) species [14,15] or generating them insitu from the corresponding iodoarenes with the aid of oxidizers (Scheme 1, b). [16][17][18] Despite the broad applicability of the above-mentioned syntheses, they suffer from disadvantages in terms of sustainability, safety and cost efficiency. Often prefunctionalized substrates, expensive transition metal catalysts, and stoichiometric amounts of highly reactive oxidizers are required.…”

Progress in organocatalysis with hypervalent iodine catalysts

“…In 2022, Kita and co-workers designed an efficient method to synthesize benzolactams 32 via an intramolecular C–H amination of aryl amides 29 using biaryl-based iodoarene precatalyst 30 . 73 The reaction involves the in situ generation of μ-oxo hypervalent iodine compound 31 through the oxidation of iodoarene 30 using m CPBA as oxidant (Scheme 6). When 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was used as solvent, the desired benzolactams 32 were obtained in higher yields.…”

New Isoxazole‐Substituted Aryl Iodides: Metal‐Free Synthesis, Characterization and Catalytic Activity

“…[2,5,17] Certain alternative approaches for the oxidation of sulfides to sulfoxides include electrochemical methods, [18] photocatalytic oxidation using oxygen [19] etc. Besides oxidation reactions, various other valuable reactions such as alkene difunctionalization, [20][21] spiro cyclization of esters and amides [22][23] and oxytosylation and acetylation of ketones [24] have also been studied by the use of iodoarenes as catalysts. Recently, Nachtsheim group developed N-heterocyclic iodoarenes (NHIAs) as efficient organocatalysts in various oxidative transformations.…”