A palladium-catalysed aminocarbonylation of (hetero)aryl iodides has, for the first time, been accomplished in deep eutectic solvents as environmentally benign and recyclable media, under mild conditions. The reactions proceeded with a good substrate scope, and a variety of amides have been synthesized in yields up to 98%.

Abstract:A high-yield one-pot two-step synthesis of 2-aminoimidazoles (2-AI), exploiting an under-air heterocyclodehydration process between α-chloroketones and guanidine derivatives, and using deep eutectic solvents (DESs) as nonconventional, "green" and "innocent" reaction media, has been accomplished successfully. The combination of either glycerol or urea with choline chloride (ChCl) proved to be effective for decreasing the reaction time to about 4-6 h in contrast to the 10-12 h usually required for the same reaction run in toxic and volatile organic solvents and under an argon atmosphere. In addition, the use of the ChCl-urea as a DES also enables the direct isolation of triaryl-substituted 2-AI derivatives by means of a simple work-up procedure consisting in filtration and crystallization, and allows the recycle of the DES mixture. A plausible mechanism highlighting the potential role played by hydrogen bonding catalysis has also been illustrated.

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A short and efficient one-pot synthesis of uracil derivatives with a high structural variability is described. The process is a multicomponent reaction based on a palladium-catalyzed carbonylation of α-chloroketones in the presence of primary amines and isocyanates. In most cases, when the formation of unsymmetrical N,N'-disubstituted uracil derivatives can occur, the methodology demonstrates to be highly regioselective. A mechanistic hypothesis involving β-dicarbonyl palladium intermediates and urea derivatives, generated in situ, has been discussed.

A valuable and direct method for the synthesis of 2‐aminopyrimidin‐4‐one derivatives is described. The strategy relies on the Pd‐catalysed carbonylation of α‐chloro ketones in the presence of mono‐ and disubstituted guanidines. Although the strategy also gave 2‐aminoimidazole derivatives as minor products, good chemoselectivity in favour of the six‐membered ring was achieved in all experiments. The in‐situ formation of a (β‐oxoacyl)palladium species has been invoked as the key step for the multicomponent process. Moreover, the method described could be of interest from a biological point of view, because it constitutes a straightforward strategy for the synthesis of structural analogues of the unnatural nucleobase isocytosine.

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A new mild and high yielding methodology for concomitant C—C and C—O or C—N bond formation across α‐chloroimines or chloromethyl heteroaromatic rings containing a C—N double bond is developed.