Regio- and stereoselective hydroxybromination and dibromination of olefins using ammonium bromide and oxone®

An efficient protocol for the synthesis of vicinal bromohydrins and dibromides from olefins is presented. Various olefins are regio- and stereoselectively hydroxybrominated and dibrominated with anti fashion, following Markonikov’s rule, using eco-friendly, non-toxic, and stable reagents such as NH₄Br and oxone® in CH₃CN/H₂O (1:1) and CH₃CN without employing catalyst in moderate to excellent yields. Bromohydrins are formed instantaneously.     

Alkoxybromination of Olefins Using Ammonium Bromide and Oxone

A mild, efficient, and highly regio- and stereoselective method for the methoxy and ethoxy bromination of olefins has been developed using NH₄Br as a bromine source and Oxone as an oxidant. Various kinds of olefins (aromatic, linear, and cyclic olefins) afforded the corresponding alkoxy brominated products in moderate to excellent yields.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]     

Oxidative bromination of ketones using ammonium bromide and oxone®

A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone® as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system.     

Synthesis,Characterization, and Catalytic Activity of Metallo Octamethylcalix (4) Pyridino Complexes Encapsulated in MCM-41

The synthesis and encapsulation of M⁺ⁿ-octamethylcalix(4)pyridino complexes using acetone and pyridine in H-MCM-41 have been achieved and presented. These hybrid catalysts are characterized by x-ray diffraction, infrared, thermal analysis, Brunauer–Emmett–Teller (BET) surface area, and scanning electron microscopy and tested for catalytic activity. They are active in the liquid-phase oxidation of p-xylene using H₂O₂ as oxidant and acetic acid as solvent in the temperature range of 30–100 °C. The variation of central transition-metal cation and the heterocyclic ring in the metallomacrocycle influence the catalytic activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Iodination of Aromatic Compounds Using Potassium Iodide and Hydrogen Peroxide

A simple, efficient, regioselective, and ecofriendly method for oxyiodination of aromatic compounds is presented. In this method, the electrophilic substitutions of iodine generated in situ from KI as an iodine source and hydrogen peroxide as an oxygen source have been employed without any catalyst/mineral acid for the first time.