Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne structural motifs to provide the functionalized pyridine and pyrrole derivatives. The functionalization reactions cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, and hydroxylation. We also briefly introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles.

Photocatalytic Deoxygenation of N–O Bonds with Rhenium Complexes: From the Reduction of Nitrous Oxide to Pyridine N-Oxides

The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. The large spectrum of reduction potentials covered by nitrogen oxides makes it however difficult to find general systems capable of efficiently reducing various N-oxides. Here photocatalysis unlocks high energy species able to both circumvent the inherent low reactivity of the greenhouse gas and oxidant N₂O (E°(N₂O/N₂) = +1.77 V vs. SHE), and reduce pyridine N-oxides (E_1/2(pyridine N-oxide/pyridine) = –1.04 V vs. SHE). The rhenium complex [Re(4,4’-tBu-bpy)(CO)₃Cl] proved to be efficient to perform both reactions under ambient conditions, enabling the deoxygenation of N₂O as well as synthetically relevant and functionalized pyridine N-oxides.<br>

Photocatalytic Deoxygenation of N–O Bonds with Rhenium Complexes: From the Reduction of Nitrous Oxide to Pyridine N-Oxides

The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. The large spectrum of reduction potentials covered by nitrogen oxides makes it however difficult to find general systems capable of efficiently reducing various N-oxides. Here photocatalysis unlocks high energy species able to both circumvent the inherent low reactivity of the greenhouse gas and oxidant N₂O (E°(N₂O/N₂) = +1.77 V vs. SHE), and reduce pyridine N-oxides (E_1/2(pyridine N-oxide/pyridine) = –1.04 V vs. SHE). The rhenium complex [Re(4,4’-tBu-bpy)(CO)₃Cl] proved to be efficient to perform both reactions under ambient conditions, enabling the deoxygenation of N₂O as well as synthetically relevant and functionalized pyridine N-oxides.<br>

Correction: Functionalized pyridine in pyclen-based iron(iii) complexes: evaluation of fundamental properties

Correction for ‘Functionalized pyridine in pyclen-based iron(iii) complexes: evaluation of fundamental properties’ by Magy A. Mekhail et al., RSC Adv., 2020, 10, 31165–31170. DOI: 10.1039/d0ra05756h.

[{AgL}2Mo8O26]n– complexes: a combined experimental and theoretical study

Two sets of silver–molybdate complexes with L = XR3 (X = P, As, Sb; R3 = Ph3, Ph2Py) and functionalized pyridine-based ligands have been studied with different techniques.

Functionalized pyridine in pyclen-based iron(iii) complexes: evaluation of fundamental properties

Six iron(iii) pyridinophane complexes were evaluated to determine whether functionalizing the pyridine ring could introduce a handle by which electrochemical properties and thermodynamic stability can be tuned.