Chemoselective Addition of Organozinc Reagents to Carbonyl Compounds, Nitrosoalkenes and β-Nitroolefines in Deep Eutectic Solvent

Nowadays, basic and applied chemistry is generally performed in toxic, hazardous and volatile organic solvents, which are responsible for most waste generated in the chemical industries and laboratories. During the past decade, a new generation of solvents, denominated Deep Eutectic Solvents (DESs), begun to emerge. DESs are generally composed of a mixture of two or three safe and renewable compounds (e.g. choline chloride, urea, glycerol, D-glucose, etc.) able to engage in hydrogen-bond interactions with each other to form an eutectic mixture with a melting point much lower (hence "deep") than either of the individual components. I Recent pioneering work from our and other laboratories worldwide have shown the potential of DESs as superior green and biorenewable reaction media also for highly polar organometallic compounds such as Grignard and organolithium reagents. 2 Building on these recent findings, in this communication we wish to report the first nucleophilic additions by organozinc reagents to carbonyl derivatives and P-nitroolefines in DESs or in low melting mixtures (LMMs), respectively. Of note, the above additions could be successfully performed under air and moderate heating, and without a ligand that is usually required to activate the organozinc compound. The first nucleophilic alkylation and sulfenylation in DESS of in situ generated nitrosoalkenes leading to cc-alkylated and sulfenylated ketones, respectively, will also be discussed. Such a transformation overall proceeds in an umpolung fashion relative to classical enolate/azaenolate methods. l) Alonso, D. A.; Baza, A.; Chinchilla, R.; Guillena, G.; Pastor, l, M.; Ramón, D. J. Eur. J. Org. Chem. 2016, 612—632. 2) Mallardo, V.; Rizzi, R.; Sassone, F.; Mansueto, R.; Perna, F. M.; Salomone, A.; Capriati, V. Chem. Commun. 2014, 50, 8655-8658. 3) Sassone, F. C.; Perna, F. Salomone, A.; Florio, S.; Capriati, V. Chem. Commun. 2015, 51, 9459—9462. 4) Cicco, L.; Sblendorio, S.; Mansueto, R.; Perna, F. M.; Salomone, Florio, S.; Capriati, V. Chem. Sci. 2016, 7, 1 192-1 199. 5) Garcia-Alvarez, Hevia, Capriati, V. Eur. J. Org. Chem. 2015, 31, 6779-6799.