Lactamization of sp² C−H Bonds with CO₂: Transition‐Metal‐Free and Redox‐Neutral

Abstract

The first direct use of carbon dioxide in the lactamization of alkenyl and heteroaryl C-H bonds to synthesize important 2-quinolinones and polyheterocycles in moderate to excellent yields is reported. Carbon dioxide, a nontoxic, inexpensive, and readily available greenhouse gas, acts as an ideal carbonyl source. Importantly, this transition-metal-free and redox-neutral process is eco-friendly and desirable for the pharmaceutical industry. Moreover, these reactions feature a broad substrate scope, good functional group tolerance, facile scalability, and easy product derivatization.

Catalytic Intermolecular Dicarbofunctionalization of Styrenes with CO2 and Radical Precursors

“…[9] If successful, such as cenario might unravel am ultifaceted challenge,not only providing the synergistic merger of visiblelight photoredox catalysis and CO 2 with p-systems, [10,11] but also offering an unrecognized opportunity in catalytic carboxylations to enable multiple,i ntermolecular C À Cb ond formations. [12,13] Herein, we report the successful realization of this goal. This protocol operates at atmospheric pressure of CO 2 without the need for organic (pseudo)halides [4] or stoichiometric reductants.…”

Bio‐Inspired Fragmentations: Rapid Assembly of Indolones, 2‐Quinolinones, and (−)‐Goniomitine

“…We quickly recognized that this undesired result could be harnessed for the syntheses of multi-functionalized 2-quinolinones,the privileged heterocyclic structures in medicinal chemistry. [11] While numerous synthetic methods for the preparation of 2-quinolinones have been reported, [12] few of them could allow for the introduction of several functional groups into the heterocyclic scaffold. Thef unctional groups on am edicinally important architecture could be used either individually as synthetic handles or for functional-group-pairing reactions, [13] generating compound libraries through diversity-oriented synthesis.…”

Direct Carboxylation of C(sp3)-H and C(sp2)-H Bonds with CO2 by Transition-Metal-Catalyzed and Base-Mediated Reactions

“…Yu and coworkers succeded in obtaining the first example of lactamization of 2-alkenylanilines (158) with CO 2 to form 2-quinolinone derivatives (159) in high yields (26 examples, 42-95% yields) under atmospheric pressure (Scheme 68a) [145]. The 2-quinolinone motif is widely exploited in synthetic medicinal chemistry and photoelectric materials [146][147][148] and was previously accessed by the groups of Alper [149], Zhu [150] and Chuang [151] via lactamization of alkenyl and aryl C-H bonds with CO. Yu implemented, thus, a lactonization reaction using CO 2 founding that 2-alkenylanilines with R 2 = CH 3 (Scheme 68a) are more reactive than substrates with R 2 = H, Et.…”