Direct reduction of unactivated alkyl halides for C(sp3)-N couplings under mild conditions presents a significant challenge in organic synthesis due to their low reduction potential. Herein, we introduce an in situ formed pyridyl-carbene-ligated copper (I) catalyst that is capable of abstracting halide atom and generating alkyl radicals for general C(sp3)-N couplings under visible light. Control experiments confirmed that the mono-pyridyl-carbene-ligated copper complex is the active species responsible for catalysis. Mechanistic investigations using transient absorption spectroscopy across multiple decades of timescales revealed ultrafast intersystem crossing (260 ps) of the photoexcited copper (I) complexes into their long-lived triplet excited states (>2 μs). The non-Stern-Volmer quenching dynamics of the triplets by unactivated alkyl halides suggests an association between copper (I) complexes and alkyl halides, thereby facilitating the abstraction of halide atoms via inner-sphere single electron transfer (SET), rather than outer-sphere SET, for the formation of alkyl radicals for subsequent cross couplings.

Pyrroles are important N-heterocycles found in medicines and materials. The formation of pyrroles from widely accessible pyrrolidines is a potentially attractive strategy but is an underdeveloped approach due to the sensitivity of pyrroles to the oxidative conditions required to achieve such a transformation. Herein, we report a catalytic approach that employs commercially available B(C₆F₅)₃ in an operationally simple procedure that allows pyrrolidines to serve as direct synthons for pyrroles. Mechanistic studies have revealed insights into borane-catalyzed dehydrogenative processes.

A convenient synthetic route to polycyclic metallaaromatics containing main-group heteroatoms has been developed. The first cyclopropametalla-2-benzopyrylium complexes 2–4, the rhena-analogues of pyrylium, are isolated and characterized. Structural analysis and DFT calculations show that the metalla-oxa polycyclic structures have both π-aromaticity and σ-aromaticity.

Anilido-oxazoline-ligated rare-earth metal dialkyl complexes have been synthesized and structurally characterized. The complexes exhibited strong fluorescence emissions and good catalytic performance on isoprene polymerization with high cis-1,4-selectivity. The treatment of anilido-oxazoline precursors ortho-C₆H₄[NH(2,6-R¹ ₂C₆H₃)][CNC(R²,R³)CH₂O] (R¹ = R² = R³ = Me (HL¹); R¹ = ⁱPr, R² = R³ = Me (HL²); R¹ = R² = ⁱPr, R³ = H (HL³); and R¹ = ⁱPr, R² = R³ = H (HL⁴)) with an equimolar amount of Ln(CH₂SiMe₃)₃(THF)₂ (Ln = Sc, Y) afforded rare-earth metal complexes L^1–4-Ln(CH₂SiMe₃)₂(THF)_n (L¹-Sc (1), n = 1; L²-Sc (2), n = 0; L¹-Y (3), n = 1; L²-Y (4), n = 1; L³-Y (5), n = 1; and L⁴-Y (6), n = 1) in good yields. The complexes are stable in both the solid state and solution. Single crystal X-ray diffraction study showed that complexes 1, 3 and 4 exhibit a distorted trigonal bipyramidal configuration, while complex 2 is pseudo-tetrahedral without coordinated THF. The luminescence properties of complexes 1–4 were investigated and the emission maxima were found in the range of 465–477 nm. DFT and TD-DFT studies were carried out to explore their characteristic electronic structures and gain insight into their optical properties. Upon activation with organic borates, the reported complexes exhibited high activity and cis-1,4-selectivity for isoprene polymerization. The nature of the central metal and substituent groups in oxazoline have an influence on the cis-1,4-selectivity.