NBS-Mediated Oxygen Transfer Reaction of Carbonyl in Ester: Efficient Synthesis of Benzil-o -carboxylate Derivative From o -Alkynylbenzoate

FeIII -Based Eutectic Mixtures as Multi-task and Reusable Reaction Media for Efficient and Selective Conversion of Alkynes into Carbonyl Compounds

An efficient, simple and general protocol for the selective hydration of terminal alkynes into the corresponding methyl ketones has been developed by using a cheap, easy-to-synthesise and sustainable FeIII -based eutectic mixture [FeCl3  ⋅ 6H2 O/Gly (3 : 1)] as both promoter and solvent for the hydration reaction, working: i) under mild (45 °C) and bench-type reaction conditions (air); and ii) in the absence of ligands, co-catalysts, co-solvents or toxic, non-abundant and expensive noble transition metals (Au, Ru, Pd). When the final methyl ketones are solid/insoluble in the eutectic mixture, the hydration reaction takes place in 30 min, and the obtained methyl ketones can be isolated by simply decanting the liquid FeIII -DES, allowing the direct isolation of the desired ketones without VOC solvents. By using this straightforward and simple isolation protocol, we have been able to recycle the FeIII -based eutectic mixture system up to eight consecutive times. Furthermore, the FeIII -eutectic mixture is able to promote the selective and efficient formal oxidation of internal alkynes into 1,2-diketones, with the possibility of recycling this system up to three consecutive times. Preliminary investigations into a possible mechanism for the oxidation of the internal alkynes seem to indicate that it proceeds through the formation of the corresponding methyl ketones and α-chloroketones.

Regioselective Hydrodeoxygenation of α-Diketones with Phosphites under Visible-Light Catalysis

Novel regioselective hydrodeoxygenation of α-diketones with phosphites as the deoxygenation reagent was realized via visible-light photoredox catalysis. Broad substrate scope and high functional group compatibility were obtained. Unsymmetric α-diketones were selectively reduced at the carbonyls of higher electrophilicity. This unique regioselectivity compared with available methods makes it a practical complementary approach for the monohydrodeoxygenation of α-diketones.

NBS-induced intramolecular annulation reactions for the divergent synthesis of fused- and spirocyclic indolines

An NBS-induced intramolecular annulation of 3-(1H-indol-3-yl)-N-alkoxypropanamide is described. The reactions proceed well and quickly under mild conditions with the help of a base. It was found that C2-substituents on the indole ring in 3-(1H-indol-3-yl)-N-alkoxypropanamide have a great influence upon the reaction. By using C2-methyl- and C2-phenyl-3-(1H-indol-3-yl)-N-alkoxypropanamide as templates, practical protocols for the divergent synthesis of fused- and spirocyclic indoline compounds were studied and established.

Csp–Csp bond cleavage and fragment coupling: a transition metal-free “extrusion and recombination” approach towards synthesis of 1,2-diketones

A metal-free strategy for C–C bond activation of 1,3-diynes has been established via an “extrusion and recombination” approach to derive structurally important 1,2-diketones in good yields with excellent selectivity.

Recent advances in the direct β-C(sp2)–H functionalization of enamides

Recent advances in the direct β-C(sp²)–H functionalization of enamides, mainly including arylation, alkenylation, alkynylation, alkylation, acylation, sulfonylation, phosphorylation, and others, are reported.

Photoinduced synthesis of 2-sulfonylacetonitriles with the insertion of sulfur dioxide under ultraviolet irradiation

Metal-free insertion of sulfur dioxide with aryl iodides and 3-azido-2-methylbut-3-en-2-ol under ultraviolet irradiation at room temperature is achieved, giving rise to 2-(arylsulfonyl)acetonitriles in moderate to good yields. Alkyl iodide is also workable under these conditions. This transformation proceeds smoothly under mild conditions with a broad substrate scope. Various functional groups are compatible including amino, ester, halo, and trifluoromethyl groups. No metal catalyst or additive is needed during the reaction process. Mechanistic studies show that under ultraviolet irradiation, an aryl radical is generated in situ from aryl iodide, which undergoes subsequent sulfonylation via the insertion of sulfur dioxide leading to arylsulfonyl radical intermediates. Then the arylsulfonyl radical reacts with 3-azido-2-methylbut-3-en-2-ol giving rise to the corresponding 2-(arylsulfonyl)acetonitrile.

Oxidative oxy-cyclization of 2-alkynylbenzamide enabled by TBAB/Oxone: switchable synthesis of isocoumarin-1-imines and isobenzofuran-1-imine

A TBAB-controlled switchable synthesis of isocoumarin-1-imine and isobenzofuran-1-imine from 2-alkynylbenzamide in water is described in this paper.

Synthesis of benzil-o-carboxylate derivatives and isocoumarins through neighboring ester-participating bromocyclizations of o-alkynylbenzoates

Neighboring ester-participating bromocyclizations of o-alkynylbenzoates are developed for the switchable synthesis of benzil-o-carboxylate derivatives and isocoumarins.