A highly efficient and flexible protocol for intramolecular annulation of exocyclic β‐enaminones has been disclosed for the synthesis of carbazolones and imidazo[1,2‐a]pyridines through a counter‐anion‐controlled free‐radical mechanism promoted by hypervalent iodine(III). The cooperative behavior of HTIB and AgSbF6 plays a crucial role in the intramolecular annulation process through C−C and C−N bond formation to give the desired products. The mechanistic insights suggest that the two competitive reactions involved in the system are guided by the nature of the counteranion, which determines the formation of the final products. A wide variety of carbazolones and imidazo[1,2‐a]pyridine molecules have been prepared and isolated in good to excellent yields.

A decarbonylation free, polystyrene-supported, Pd (Pd@PS)-catalysed carbonylative esterification of the hydroxy group of 5-hydroxymethyl furfural (5-HMF) to its corresponding aryl esters has been developed. The use of Pd@PS, oxalic acid as CO source, and aryl halides was first explored for the aryl ester of 5-HMF synthesis. Here, we investigated the vital role of a polystyrene support to avoid the commonly known decarbonylation of 5-HMF. The reaction exhibits vast substrate scope with comparably good yield and catalyst recyclability.

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An efficient and convenient strategy for the synthesis of diversely substituted quinazolinones from o‐carbamoyl/cyano aniline and aryl iodides using oxalic acid as a CO source under polystyrene supported palladium (Pd@PS) nanoparticles (NPs) catalyzed conditions has been developed. In this study, oxalic acid has been employed as safe, economic, environmentally benign, sustainable and bench‐stable, solid CO surrogate under Double‐Layer‐Vial (DLV) system for the synthesis of 2‐aryl quinazolinones. This methodology does not require any special high‐pressure equipment like autoclaves, microwaves, etc. Moreover, a simple procedure for catalyst preparation, catalyst recyclability, easy handling of reaction, additive and base‐free generation of CO, excellent to good yields and vast substrate scope are the additional features of developed protocol.

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The polystyrene supported palladium-gold (PdÀ Au@PS) catalyst was prepared and well characterized by HR-TEM, EDX, Elemental Mapping, XPS and P-XRD analysis. The PdÀ Au@PS NPs displayed the superior catalytic activity than their monometallic forms. First time, the catalyst was applied for methylthioesterification reaction of aryl iodides with oxalic acid and DMSO as in situ carbon monoxide (CO) and methyl mercaptan (CH 3 SH) precursor. Yet, there is no report available where DMSO has been applied as CH 3 SH source for methylthioester synthesis. The CH 3 SH and CO are likely to poison the metal catalyst whereas in PdÀ Au@PS catalyst, the beneficial inter-electronic interactions between Pd and Au metals makes the catalyst highly reactive, poisoning resistant and recyclable during the transformation. Moreover, the developed protocol exhibits excellent functional group tolerance for various aryl iodides to delivered the desired products in moderate to very good yields.

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The overabundance and environmental concerns of agro-waste highly demand sustainable and economical pathways for furanic compounds synthesis as alternatives of energy and important industrial materials. In this review, we summarized...