Towards Uniform Iodine Catalysis: Intramolecular C-H Amination of Arenes under Visible Light

A photochemical catalytic amination of arenes is presented. The reaction proceeds under benign iodine catalysis in the presence of visible light as the initiator and provides access to a range of differently substituted arylamines. A total of 29 examples demonstrate the broad applicability of this mild oxidation method. The scope of the reaction could further be expanded to silyl-tethered derivatives, which undergo intramolecular amination upon formation of seven-membered heterocycles. Cleavage of the silicon tether provides access to the corresponding 3-substituted anilines.

Enantioselective Sulfoxidation Catalyzed by a Bisguanidinium Diphosphatobisperoxotungstate Ion Pair

The first enantioselective tungstate-catalyzed oxidation reaction is presented. High enantioselectivities were achieved for a variety of drug-like phenyl and heterocyclic sulfides under mild conditions with H2 O2 , a cheap and environmentally friendly oxidant. Synthetic utility was demonstrated through the preparation of (S)-Lansoprazole, a commercial proton-pump inhibitor. The active ion-pair catalyst was identified to be bisguanidinium diphosphatobisperoxotungstate using Raman spectroscopy and computational studies.

KI-catalyzed α-acyloxylation of acetone with carboxylic acids

A KI catalyzed reaction of acetone with aromatic carboxylic acids is achieved, leading to α-acyloxycarbonyl compounds in good to excellent yields under mild reaction conditions. The present method exhibits good functional-group compatibility.

Hypoiodite-catalysed oxidative cyclisation of Michael adducts of chalcones with 1,3-dicarbonyl compounds: a facile and versatile approach to substituted furans and cyclopropanes

Hypoiodite catalysis for selective oxidative cyclization has been developed, yielding either furans or cyclopropanes with excellent diastereoselectivity.

Cobalt(ii)-catalyzed oxidative esterification of aldehydes: a cooperative effect between cobalt and iodide ions

Efficient cobalt(ii) catalyzed oxidative alkoxylation of aldehydes leading to the corresponding esters is presented. Mechanism studies provide fresh insights into the cobalt mediated decomposition of TBHP in the presence of the iodide ion.

Photocycloaddition reaction of atropisomeric maleimides: mechanism and selectivity

We report a density functional study on the mechanism of the [2+2] photocyclization of atropisomeric maleimides.

[3 + 2] cycloaddition and subsequent oxidative dehydrogenation between alkenes and diazo compounds: a simple and direct approach to pyrazoles using TBAI/TBHP

Herein, an efficient [3 + 2] cycloaddition and oxidative dehydrogenation reaction of diazo compounds and alkenes was well developed using TBAI/TBHP, leading to pyrazoles with moderate to high yields.

Cd(ii)-MOF-IM: post-synthesis functionalization of a Cd(ii)-MOF as a triphase transfer catalyst

The post-synthetically imidazolium decorated Cd(ii)-MOF-IM can be a highly active triphase transfer catalyst to promote the azidation and thiolation of bromoalkanes between aqueous and organic phases.

Transition-metal-free decarboxylation of dimethyl malonate: an efficient construction of α-amino acid esters using TBAI/TBHP

A transition-metal-free decarboxylation coupling process for the preparation of α-amino acid esters, which succeeded in merging hydrolysis/decarboxylation/nucleophilic substitution, is well described. This strategy uses commercially available inexpensive starting materials, catalysts and oxidants and has a wide substrate scope and operational simplicity.

Enantioselective Oxidation of Alkenes with Potassium Permanganate Catalyzed by Chiral Dicationic Bisguanidinium

Chiral anion-controlled ion-pairing catalysis was demonstrated to be a wide-ranging strategy that can utilize a variety of cationic metal species. In a similar manner, we envision a complementary strategy using chiral cation in partnership with inorganic anionic metal salts. Herein, we report a chiral dicationic bisguanidinium-catalyzed asymmetric oxidation reaction of alkenes with potassium permanganate. Chiral induction is attributed to ion-pairing interaction between chiral cation and enolate anion. The success of the current permanganate oxidation reaction together with mechanistic insights should provide inspiration for expansion to other anionic metal salts and would open up new paradigms for asymmetric transition metal catalysis, phase-transfer catalysis, and ion-pairing catalysis.

Mechanistic insights on the iodine(III)-mediated α-oxidation of ketones

The synthesis of α-substituted carbonyl compounds is of great importance due to their ubiquity in both natural and man-made biologically active compounds. The field of hypervalent iodine chemistry has been a great contributor to access these molecules. For example, the α-oxidation of carbonyl compounds has been one of the most investigated iodine(III)-mediated stereoselective transformations. Yet, it is also the transformation that has met the most challenge in terms of achieving high stereoselectivities. The different mechanistic pathways of the iodine(III)-mediated α-tosyloxylation of ketones have been investigated. The calculations suggest an unprecedented iodine(III)-promoted enolization process. Indications that iodonium intermediates could serve as proficient Lewis acids are reported. This concept could have broad impact and foster new developments in the field of hypervalent iodine chemistry.

Aerobic photooxidative synthesis of 2-aryl-4-quinazolinones from aromatic aldehydes and aminobenzamide using catalytic amounts of molecular iodine

This study reports a safe, mild, and environmentally benign synthetic method toward 2-aryl-4-quinazolinones through a cyclization–oxidation sequence using a catalytic amount of iodine, harmless visible light irradiation, and molecular oxygen.

Guanidinium iodide-catalyzed oxidative α-nitroalkylation of β-ketoamides

Oxidative nitroalkylation of β-ketoamides and nitroalkanes, mediated by hypoiodide generated from tert-butyl hydrogen peroxide and a catalytic amount of guanidinium iodide, afforded the corresponding α-nitroalkyl-β-ketoamides in up to 97% yield.

Metal-free synthesis of imidazopyridine from nitroalkene and 2-aminopyridine in the presence of a catalytic amount of iodine and aqueous hydrogen peroxide

We have developed a metal-free synthetic method for 3-nitroimidazo[1,2-a]pyridines from nitroalkenes and 2-aminopyridines using catalytic amounts of iodine and aqueous hydrogen peroxide as a terminal oxidant.

Enhancement of stereoselectivities in asymmetric synthesis using fluorinated solvents, auxiliaries, and catalysts

In this review, the drastic changes using fluorinated solvents, additives, auxiliaries, and catalysts in catalytic asymmetric transformations are presented.

Total synthesis of (R,R,R)-γ-tocopherol through Cu-catalyzed asymmetric 1,2-addition

Based on the asymmetric copper-catalyzed 1,2-addition of Grignard reagents to ketones, (R,R,R)-γ-tocopherol has been synthesized in 36 % yield over 12 steps (longest linear sequence). The chiral center in the chroman ring was constructed with 73 % ee by the 1,2-addition of a phytol-derived Grignard reagent to an α-bromo enone prepared from 2,3-dimethylquinone.