Shaanxi University of Science and Technology, Nan Jiang OL: Oxazolones as Novel Carbonylation Reagents in C–H [5+1] Carbonylative Cyclization with 2-Alkenyl- or 2-Pyrrolylanilines

Carbonylation is one of the most efficient methods for directly constructing carbonyl-containing compounds. Carbonylation reactions involving CO and its surrogates have been extensively studied; however, challenges remain—including high-pressure conditions, toxicity of CO, reliance on expensive noble-metal catalysts, and the need for stoichiometric oxidants. Thus, the continuous development of novel carbonylation reagents remains highly significant. A research group led by Associate Professor Nan Jiang at Shaanxi University of Science and Technology has successfully developed oxazolones as new carbonylation reagents, enabling a metal-free, oxidant-free [5+1] cyclization with 2-alkenyl- and 2-pyrrolylanilines to construct diverse quinolinone and pyrroloquinoxalinone scaffolds (Figure 1). The corresponding work was published online in Org. Lett. (DOI: 10.1021/acs.orglett.1c01147). Carbonylation represents a pivotal strategy for synthesizing carbonyl-containing compounds. Despite extensive reports on CO- and surrogate-mediated carbonylations, issues such as harsh reaction conditions, use of precious-metal catalysts, and stoichiometric oxidants persist—making the development of new carbonylation reagents and reaction paradigms urgently needed. Oxazolones are attractive due to their facile synthesis, versatile reactivity, and broad applicability in diverse chemical transformations—especially as aminating reagents in transition-metal-catalyzed C–H amination reactions (Figure 2, left). Several international and domestic research groups have achieved a series of amination transformations using oxazolones. In contrast, other reaction types mediated by oxazolones remain rare. Recently, a research group reported a metal-free method for urea formation from oxazolones and amines, proceeding via Curtius rearrangement to selectively form N–C(O) bonds (Figure 2, right). Inspired by these prior advances, the authors hypothesized that installing an electronically matched nucleophilic unit onto the urea scaffold could enable subsequent intramolecular transformation, thereby affording structurally complex, high-value cyclic carbonyl compounds. Building upon their group’s recent achievements in amino-directed [5+1] cyclizations, this study realizes a [5+1] carbonylative cyclization between 2-alkenyl-/2-pyrrolylanilines and oxazolones (Figure 3), successfully constructing quinolinone and pyridoquinoxalinone frameworks—structural motifs widely found in pharmaceutical agents.

Professor Guohui Yang: Recent Advances in Zeolite Catalysts for Dimethyl Ether Carbonylation

■ Keywords Dimethyl ether; Carbonylation; Methyl acetate; Reaction mechanism; Zeolite Innovations • Systematic horizontal comparison of various zeolite catalysts—particularly mordenite—in dimethyl ether (DME) carbonylation, revealing commonalities and differences in reaction pathway selectivity and deactivation behavior; • Integration of mechanistic understanding with structure–performance correlation analysis to systematically elucidate the nature of active sites, root causes of coking-induced deactivation, and mass-transfer limitations—providing theoretical foundations for precise catalytic performance modulation; • Comprehensive review of modification strategies targeting active-center distribution control, suppression of acid sites responsible for coking, and optimization of pore architecture—alongside summaries of catalyst regeneration behavior, preparation protocols, and shaping technologies—offering practical guidance for developing highly efficient and stable zeolite catalysts. Abstract Carbon-containing resources—via syngas as a hub—can be converted into methyl acetate through DME carbonylation. Subsequent hydrogenation of methyl acetate to ethanol proceeds under mild conditions, employs low-cost, easily prepared catalysts, and thus represents a crucial route for clean, efficient utilization of carbon resources—including coal—and especially for upgrading coal into high-value chemicals. DME carbonylation constitutes the core step of this process, and zeolite catalysts have attracted widespread attention for this transformation. This review summarizes recent progress in reaction pathway and deactivation mechanism studies of zeolite catalysts in DME carbonylation, discusses applications of various zeolites—especially mordenite—and identifies the nature of active sites in zeolite catalysts. Based on insights into reaction pathways, deactivation mechanisms, and active sites, we further outline zeolite catalyst modification strategies. These strategies primarily aim to: (i) precisely regulate the number and spatial distribution of active centers; (ii) effectively suppress acidic sites responsible for coking; and (iii) enhance mass-transfer efficiency by optimizing crystal size or pore architecture. Specific efforts focus on tuning acidity and microstructure, and we summarize related findings on catalyst regeneration, optimization of preparation conditions, and shaping technologies. Finally, building on current research achievements, we highlight existing challenges and propose future research directions. Outlook Developing highly efficient zeolite catalysts for DME carbonylation is pivotal to advancing the coal-to-ethanol technology pathway—via syngas → DME → methyl acetate → ethanol. This article provides a systematic review of progress in zeolite catalysts for DME carbonylation. Regarding reaction mechanisms, combined experimental and theoretical studies reveal surface methoxy and surface acetyl species as key intermediates; CO insertion into surface methoxy to generate surface acetyl is the rate-determining step, occurring predominantly at Brønsted acid sites located within the 8-membered ring (8-MR) channels of zeolites. In contrast, Brønsted acid sites within the 12-membered ring (12-MR) channels of mordenite (MOR) are prone to coking and pore blockage, leading to rapid catalyst deactivation. Current zeolite modification efforts mainly target acidity modulation and diffusion enhancement. To further improve zeolite catalyst activity and stability—and accelerate industrial implementation—future research should focus on the following areas: 1) Mechanistic deepening and rational design: Deepen mechanistic understanding of DME carbonylation over different zeolites, with particular emphasis on elucidating the unique role of 12-MR channels in MOR; clarify the precise formation pathway of methyl acetate.

Metal-Free Zeolite Catalyzes Carbonylation

23 hours ago

Researchers at DICP developed a metal-free ferrierite zeolite catalyst for carbonylation, producing propanoic and isobutyric acids without precious metals. This method targets industrial applications in food preservation and pharmaceutical synthesis.

cen

2026-11-03

Metal-Free Zeolite Catalyzes Carbonylation

Metal-Free Zeolite Catalyzes Carbonylation

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