Copper­(II) pyridyliminoarylsulfonate complexes with chloride or triflate counteranions were employed in Chan–Evans–Lam (CEL) couplings of N-nucleophiles and arylboronic acids. The complexes avoided typical side reactions in CEL couplings, and an excess of boronic acid was not required. Water was tolerated, and addition of neither base nor other additives was necessary. Primary amines, acyclic and cyclic secondary amines, anilines, aminophenol, imidazole, pyrazole, and phenyltetrazole can be quantitatively arylated at either 25 or 50 °C with 2.5 mol % of the catalyst. Reaction kinetics were investigated in detail. Kinetic and spectroscopic studies provide evidence for the formation of unproductive copper–substrate complexes. Formation of an aniline–phenylboronic acid adduct was responsible for the zero-order dependence of reaction rates on phenylboronic acid concentration. Kinetic evidence indicates that the order of reaction steps is transmetalation, nucleophile coordination, and oxidation. Couplings performed poorly with electron-deficient arylboronic acids, due to a slower Cu­(II)/Cu­(III) oxidation in the catalytic cycle. Photoredox catalysis partially resolved this problem, but addition of copper acetate as an external oxidant proved to be more efficient.

Copper complexes bearing a diketimino-sulfonate ligand, LCu(NO 3 )(NCMe), were prepared and proved to be stable to water for several hours in solution. Prolonged standing in the presence of water or strong bases led to desulfonation of the ligand. LCu(NO 3 ) was inactive in the polymerization of lactide (in the presence of benzyl alcohol), but showed high activity for the Chan−Evans−Lam coupling of a variety of amines and anilines. Couplings do not require addition of base, ligand, or molecular sieves. Mechanistic investigations indicate a catalytic cycle involving dioxygen as the required oxidant, precoordination of boronic acid to the sulfonate group, and transmetalation occurring prior to reaction with the nucleophile.

The ring-opening polymerization (ROP) of bio-derived six-membered (substituted) -valerolactones, including the -Me substituted δ-valerolactone (aka δ-hexalactone (HL)), 2-ethylidene-6-hepten-5-olide (EVL), 2-ethylheptane-5-olide (EHO) and the novel 2-ethylidene-6-heptan-5-olide (MH), is investigated. In comparison to the ubiquitous unsubstituted δ-valerolactone (VL), the presence of a substituent on the lactone ring appears to significantly affect the polymerizability of the monomer, whichever the catalyst/initiator system or the operating conditions. Typical Brönsted acids, organocatalysts or Lewis acidic metal complexes revealed hardly active in the ROP of HL, most likely originating from polymerization/depolymerization issues. Better efficiency was achieved from alkali metal complexes, especially using NaOMe (1 mol%) from which high-to-quantitative HL conversion was reached within 18 h at 60 °C.Oligomers (M̅ n,NMR < 3800 g.mol 1 , Ð M = 1.221.36) were thus synthesized from ROP, as supported by NMR spectroscopy, SEC and MALDI-ToF mass spectrometry analyses. P(HL-co-VL) random copolymers incorporating up to 44 mol% of HL into PVL were next synthesized from the simultaneous HL/VL copolymerization mediated by NaOMe (M̅ n,NMR up to 9700 g.mol 1 , Ð M = 1.211.40). The ROP of the sustainable CO 2 /butadiene-derived EVL, EHO or MH -the original semi-hydrogenated parent lactone, remained unsuccessful, regardless of the catalytic system.