Synthesis and characterization of 14 new 2,2′-bipyridine metal complexes fac -M(bpy-R)(CO) 3 X (where M = Mn, X = Br or M = Re, X = Cl and R = -CF 3 , -CN, -Ph, -PhOH, -NMe 2 ) are reported. The complexes have been characterized by NMR, IR spectroscopy and elemental analysis. Single crystal X-Ray diffraction structures have been solved for Re(dpbpy)(CO) 3 Cl (dpbpy = 4,6-diphenyl-2,2′-bipyridine) and Re(hpbpy)(CO) 3 Cl (hpbpy = 4-(2-hydroxy-phenyl)-6-phenyl-2,2′-bipyridine). Electrochemical behaviors of the complexes in acetonitrile under Ar and their catalytic performances for CO 2 reduction with added water and MeOH have been investigated by cyclic voltammetry and controlled potential electrolysis. The role of the substituents on the electrochemical properties and the related over potentials required for CO 2 transformation have been analyzed. The complexes carrying only electron withdrawing groups like -CF 3 , -CN totally lose their catalytic activities toward CO 2 reduction, whereas the symmetric -NMe 2 substituted and push-pull systems (containing both -NMe 2 and -CF 3 ) still display electrocatalytic current enhancement under CO 2 atmosphere. The complexes carrying a phenyl or a phenol group in position 4 show catalytic behaviors similar to those of simple M-bpy systems. The only detected reduction product by GC analysis is CO: for example, fac -Re (bpy-4,4′-NMe 2 )(CO) 3 Cl gives CO with high faradic efficiency and a TON of 18 and 31, in absence of external proton source and with 5% MeOH, respectively. DFT calculations were carried out to highlight the electronic properties of the complexes; results are in agreement with experimental electrochemical data.

No abstract

Tetrahydropyridazines are of particular interest for their versatility as intermediates in organic synthesis and display pharmacological activity in several domains. Here, we describe the photocatalytic synthesis of different tetrahydropyridazines starting from γ,δ-unsaturated Narylsulfonylhydrazones. Simple structural changes of substrates result into three different pathways beginning from a common N-hydrazonyl radical which evolvesthrough a dominocarboamination/dearomatization, a HAT process, or a photoinduced radical Smiles rearrangementto afford diverse tetrahydropyridazines. All reactions are carried out in very mild conditions and quite inexpensive [Ru(bpy)3]Cl2is used as the catalyst. Preliminary mechanism studies are presented, among them luminescence and electrochemical characterization of the involved species. Computational studies allow to rationalize the mechanism in accord with the experimental findings.

Organosulfur compounds have a pivotal role in the functionalities of many natural products, pharmaceuticals and organic materials. For these reason, the search for new methodologies for the formation of carbon–sulfur...

This review summarizes the most relevant advancements made in the photocatalyzed synthesis of sulfones, thioethers and sulfonamides from 2017 to the beginning of 2021. Synthetic strategies towards the construction of sulfur-carbon bonds are discussed together with the proposed reaction mechanisms. Interestingly, sulfured-based functional groups, which are of fundamental importance for the pharmaceutical field, can be assembled by photocatalysis in an easy and straightforward way in milder reaction conditions employing less toxic and expensive sulfur sources in comparison with common strategies

Among halogenated molecules, those containing chlorine atoms are fundamental in many areas such as pharmaceuticals, polymers, agrochemicals and natural metabolites. Despite the fact that many reactions have been developed to install chlorine on organic molecules, most of them rely on toxic and hazardous chlorinating reagents as well as harsh conditions. In an attempt to move towards more sustainable approaches, photoredox catalysis and electrocatalysis have emerged as powerful alternatives to traditional methods. In this review, we collect the most recent and significant examples of visible-light- or current-mediated chlorination published in the last five years.

An unprecedented visible light enhanced room temperature Heck reaction between aryl halides and allenyl tosyl amines is here reported. The simple catalytic system (Pd(OAc)2/PPh3) is exploited to afford arylated vinyl...

Here, we present an intriguing photoinduced chloroamination cyclization of allenes bearing a tethered sulfonylamido group to afford 2-(1-chlorovinyl)pyrrolidines and related heterocycles in the presence of N-chlorosuccinimide (NCS) as the chlorine source. An in depth experimental and computational mechanistic study revealed the existence of multiple reaction pathways leading to a common nitrogen centered radical (NCR). This key NCR can be, in fact, originated from (a) the oxidation of the deprotonated allene by the photoexcited state of the Ru-catalyst and (b) the photodissociation of the in situ formed N-chloroallene. The NCR formation triggers an intramolecular cyclization to a highly reactive pyrrolidine vinyl radical, which upon chlorination delivers the final product. Thus, NCS plays a dual role, serving both as an activator of the sulfonamido functionality and as the chlorinating agent.