In the last two decades, the search for sustainability in chemical reactions has attached a lot of attention. In this focus review, the use of ultrasound (US) as an alternative energy source in organic synthesis is presented. The improvement of the performance of chemical reactions due to the cavitation effect has been previously studied and described. The use of US guarantees often higher yields than other green methodologies, as microwave or ball milling. The impressive positive effect of US in organic synthesis are demonstrated in this review mainly in organometallic and multi-component reactions (MCRs), aimed to prepare bioactive compounds. A particular attention is dedicated to the US-assisted synthesis of valuable organochalcogen compounds with pharmacological activity.[a] F.

Abstract:Even if water is the natural environment for bioorganic reactions, its use in organic chemistry is often severely limited by the high insolubility of the organic derivatives. In this review, we introduce some examples of the use of water to perform organoselenium chemistry. We mainly discuss the advantages of this medium when the recyclability is demonstrated and when the water can control the selectivity of a reaction or enhance the reaction rate.

In this work, we focused our attention on seleno-Michael type reactions. These were performed using zinc-selenolates generated in situ from diphenyl diselenide 1, 1,2-bis(3-phenylpropyl)diselenide 30, and protected selenocystine 31 via an efficient biphasic Zn/HCl-based reducing system. Alkenes with a variety of electron-withdrawing groups were investigated in order to gauge the scope and limitations of the process. Results demonstrated that the addition to acyclic α,β-unsaturated ketones, aldehydes, esters amides, and acids was effectively achieved and that alkyl substituents at the reactive β-centre can be accommodated. Similarly, cyclic enones undergo efficient Se-addition and the corresponding adducts were isolated in moderate to good yield. Vinyl sulfones, α,β-unsaturated nitriles, and chalcones are not compatible with these reaction conditions. A recycling experiment demonstrated that the unreacted Zn/HCl reducing system can be effectively reused for seven reaction cycles (91% conversion yield at the 7° recycling rounds).

Easy access to mono- and bis-sulfenylindoles using the SeO2/I2 system.

We describe here an atom efficient procedure to prepare selenol esters in good to excellent yields by reacting [(PhSe)2Zn] or [(PhSe)2Zn]TMEDA with acyl chlorides under “on water” conditions. The method is applicable to a series of aromatic and aliphatic acyl chlorides and tolerates the presence of other functionalities in the starting material.