Marjan Jereb

Effective and selective iodofunctionalisation of organic molecules in water using the iodine–hydrogen peroxide tandem

Efficient hydrogen peroxide enhanced iodofunctionalisation of ketones, 1,3-dicarbonyl derivatives and activated aromatic molecules using elemental iodine in water is achieved, whereas alkynes were stereoselectively converted into (E)-1,2-diiodoalkenes.

Highly atom-economic, catalyst- and solvent-free oxidation of sulfides into sulfones using 30% aqueous H2O2

Highly atom-efficient oxidation of sulfides into sulfones under solvent- and catalyst-free reaction conditions using a 30% aqueous solution of H2O2 at 75 °C is reported. A structurally diverse set of phenyl alkyl-, phenyl benzyl-, benzyl alkyl-, dialkyl-, heteroaryl alkyl- and cyclic sulfides were transformed into sulfones regardless of the aggregate state and electronic nature of the substituents. In spite of the heterogeneous reaction mixtures throughout the work, no difficulties with stirring and reaction progress were noted. In numerous cases, only 10 mol% excess of H2O2 was used, thus contributing considerably to the high atom economy of the process. Some solid substrates required a variable excess of hydrogen peroxide; however, the reactions were performed strictly without organic solvents. The transformation was demonstrated to be amenable for scale-up with both liquid and solid sulfides. In addition, isolation and purification of the crude products can be simply done with only filtration and crystallization.

Hydrogen peroxide induced iodine transfer into alkenes

Reactions of alkenes with elemental iodine activated by 30% aqueous hydrogen peroxide in the presence of methanol or water as the external nucleophile source result in the formation of vicinal iodo-alkoxy or iodo-hydroxy substituted alkanes. Beside the fact that only 0.5 equiv. or a slight excess of hydrogen peroxide and 0.5 equiv. of iodine are sufficient amounts of reactants, this transformation is conducted in the absence of acid, thus contributing significantly to the green chemistry concept.

Direct iodination of indanone and tetralone derivatives by elemental iodine activated by selectfluor F-TEDA-BF4

Abstract Derivatives of indan-1-one and 3,4-dihydronaphthalen-1(2H)-one bearing hydroxy or methoxy substituent on the aromatic ring were efficiently iodinated regioselectively at the α carbonyl position using elemental iodine activated by 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™ F-TEDA-BF4) in methanol.

Solvent directing immediate fluorination of aromatic ketones using 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)

Reactions of aryl alkyl ketones with 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (AccufluorTM NFTh) in methanol result in selective and almost quantitative formation of the corresponding α-fluoroketones, while in acetonitrile exclusive fluorofunctionalisation of the activated aromatic ring take place.

Conversion of thiols into sulfonyl halogenides under aerobic and metal-free conditions

An environmentally benign, metal-free synthesis of sulfonyl chlorides and bromides from thiols in the presence of ammonium nitrate, an aqueous solution of HCl and HBr and oxygen as a terminal oxidant was developed. The reactivity of various substituted thiophenols, benzylic-, aliphatic- and heteroaromatic thiols was examined. Ammonium nitrate served as a source of nitrogen oxides (NO/NO2), which are the crucial players in a redox-catalytic cycle. Sulfonyl chlorides and bromides were isolated without extraction and “filtered” over a short pad of silica gel; the use of solvents was greatly reduced in comparison with traditional isolation and purification. A “one-pot” protocol for the conversion of thiol into sulfonamide is also demonstrated. Scale-up experiments on the preparation of sulfonyl chloride and bromide are shown. A possible reaction pathway is discussed.

SelectfluorTM F-TEDA-BF4 mediated and solvent directed iodination of aryl alkyl ketones using elemental iodine

Reactions of aryl alkyl ketones with methanol solution of elemental iodine and 1-fluoro-4-chloromethyl-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor F-TEDA-BF4) result in the formation of corresponding alpha-iodo ketones, while switch over of the regioselectivity can be directed by using acetonitrile as the solvent and selective iodination of the aromatic site of target molecules is thus achieved.