Chiral hypervalent iodine-catalyzed enantioselective oxidative Kita spirolactonization of 1-naphthol derivatives and one-pot diastereo-selective oxidation to epoxyspirolactones

Iodoarene-catalyzed fluorination and aminofluorination by an Ar-I/HF·pyridine/mCPBA system

We have developed the iodoarene-catalyzed fluorination of carbonyl compounds and intramolecular aminofluorination of ω-amino-alkenes using HF/mCPBA.

meta-Chloroperbenzoic acid (mCPBA): a versatile reagent in organic synthesis

This review aims to collect and discuss the synthetic applications of meta-chloroperbenzoic acid (mCPBA) over the past few decades.

Ruthenium-catalyzed hydrohydroxyalkylation of acrylates with diols and α-hydroxycarbonyl compounds to form spiro- and α-methylene-γ-butyrolactones

Under the conditions of ruthenium(0)-catalyzed hydrohydroxyalkylation, vicinal diols 1a-1l and methyl acrylate 2a are converted to the corresponding lactones 3a-3l in good to excellent yield. The reactions of methyl acrylate 2a with hydrobenzoin 1f, benzoin didehydro-1f, and benzil tetradehydro-1f form the same lactone 3f product, demonstrating that this process may be deployed in a redox level-independent manner. A variety of substituted acrylic esters 2a-2h participate in spirolactone formation, as illustrated in the conversion of N-benzyl-3-hydroxyoxindole 1o to cycloadducts 4a-4h. Hydrohydroxyalkylation of hydroxyl-substituted methacrylate 2i with diols 1b, 1f, 1j, and 1l forms α-exo-methylene-γ-butyrolactones 5b, 5f, 5j, and 5l in moderate to good yield. A catalytic cycle involving 1,2-dicarbonyl-acrylate oxidative coupling to form oxaruthenacyclic intermediates is postulated. A catalytically competent mononuclear ruthenium(II) complex was characterized by single-crystal X-ray diffraction. The influence of electronic effects on regioselectivity in reactions of nonsymmetric diols was probed using para-substituted 1-phenyl-1,2-propanediols 1g, 1m, and 1n and density functional theory calculations.

Selective electrochemical recognition of the α-naphthol isomer and in situ immobilization of naphthoquinones for tunable electrocatalysis

Fits like a glove: Separationless and selective electrochemical oxidation of the α-naphthol (α-NAP) isomer yields naphthoquinone species on the surface of multiwalled carbon nanotubes, which can further catalyze the electro-oxidation of NADH and hydrazine at different potentials. The β-NAP isomer failed to show any such electro-oxidation.

Facile oxidative rearrangements using hypervalent iodine reagents

Aromatic substituents migrate in a novel oxidative cyclization mediated by iodine(III) reagents. 4-Arylbut-3-enoic acids are cyclized and rearranged to 4-arylfuran-2(5H)-ones by hypervalent iodine compounds in good to excellent yields under mild reaction conditions. Other ring sizes are also accessible. The mechanism of the reaction is described in detail, and calculations highlight the cationic nature of the intermediates in the rearrangement. The fast access to heavily substituted furanones is used for the synthesis of biologically active derivatives.

Organoiodine(V) reagents in organic synthesis

Organohypervalent iodine reagents have attracted significant recent interest as versatile and environmentally benign oxidants with numerous applications in organic synthesis. This Perspective summarizes synthetic applications of hypervalent iodine(V) reagents: 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), pseudocyclic iodylarenes, and their recyclable polymer-supported analogues. Recent advances in the development of new catalytic systems based on the generation of hypervalent iodine species in situ are also overviewed.