Gas-free alkoxycarbonylation of aryl iodides in a phosphonium-based deep eutectic solvent with Mo(CO)6 as a solid CO source.

Pd-catalyzed alkoxycarbonylation of aryl iodides has been explored, for the first time, in phosphonium-based deep eutectic solvents under gas-free conditions, by using Mo(CO)6 as the CO source. The method allows the preparation of ethylene glycol and glycerol esters in high yields (up to 99%), short reaction times and under mild reaction conditions with a very low catalyst loading (0.5 mol%).

N-, O- and S-Heterocycles Synthesis in Deep Eutectic Solvents.

The synthesis of heterocycles is a fundamental area of organic chemistry that offers enormous potential for the discovery of new products with important applications in our daily life such as pharmaceuticals, agrochemicals, flavors, dyes, and, more generally, engineered materials with innovative properties. As heterocyclic compounds find application across multiple industries and are prepared in very large quantities, the development of sustainable approaches for their synthesis has become a crucial objective for contemporary green chemistry committed to reducing the environmental impact of chemical processes. In this context, the present review focuses on the recent methodologies aimed at preparing N-, O- and S-heterocyclic compounds in Deep Eutectic Solvents, a new class of ionic solvents that are non-volatile, non-toxic, easy to prepare, easy to recycle, and can be obtained from renewable sources. Emphasis has been placed on those processes that prioritize the recycling of catalyst and solvent, as they offer the dual benefit of promoting synthetic efficiency while demonstrating environmental responsibility.

A phosphonium-based deep eutectic solvent promotes the stereoselective semi-reduction of internal alkynes to (Z)-alkenes.

Treatment of internal alkynes with Al powder, Pd/C and basic water in a methyltriphenylphosphonium bromide/ethylene glycol eutectic mixture resulted in highly chemoselective formation of (Z)-alkenes in a yield of up to 99% with Z/E stereoselectivity ranging from 63/37 to 99/1. The unusual catalytic activity of Pd/C is thought to be modulated by the in situ formation of a phosphine ligand.

Cobalt-catalyzed cross-coupling reactions of aryl- and alkylaluminum derivatives with (hetero)aryl and alkyl bromides.

A simple cobalt complex, such as Co(phen)Cl2, turned out to be a highly efficient and cheap precatalyst for a host of cross-coupling reactions involving aromatic and aliphatic organoaluminum reagents with aryl, heteroaryl and alkyl bromides. New C(sp2)-C(sp2) and C(sp2)-C(sp3) bonds were formed in good to excellent yields and with high chemoselectivity, under mild reaction conditions.

Towards a sustainable synthesis of amides: chemoselective palladium-catalysed aminocarbonylation of aryl iodides in deep eutectic solvents.

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%.