Selective Oxidation of Clopidogrel by Peroxymonosulfate (PMS) and Sodium Halide (NaX) System: An NMR Study

A selective transformation of clopidogrel hydrogen sulfate (CLP) by reactive halogen species (HOX) generated from peroxymonosulfate (PMS) and sodium halide (NaX) is described. Other sustainable oxidants as well as different solvents have also been investigated. As result of this study, for each sodium salt the reaction conditions were optimized, and four different degradation products were formed. Three products were halogenated at C-2 on the thiophene ring and have concomitant functional transformation, such as N-oxide in the piperidine group. A halogenated endo-iminium product was also observed. With this condition, a fast preparation of known endo-iminium clopidogrel impurity (new counterion) was reported as well. The progress of the reaction was monitored using nuclear magnetic resonance spectroscopy as an analytical tool and all the products were characterized by 1D-, 2D-NMR and HRMS.

An efficient synthesis of versatile synthon 3-chlorooxindoles with NaCl/oxone

The present work describes an expedient approach for the direct conversion of indole-3-carboxaldehyde to 3-chlorooxindoles.

Efficient synthesis of esters through oxone-catalyzed dehydrogenation of carboxylic acids and alcohols

An environmentally friendly oxone (20 mol%) catalyzed esterification of carboxylic acids with alcohols has been developed, providing an attractive alternative to the construction of valuable carbonyl esters.

PhI(OAc)2/NaX-mediated halogenation providing access to valuable synthons 3-haloindole derivatives

This paper describes a mild phenyliodine diacetate mediated method for selective chlorination, bromination, and iodination of indole C–H bonds using sodium halide as a source for analogous halogenations.

Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature

A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H₂O/CF₃CH₂OH at room temperature. Other secondary and primary alkyl sp³ C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp³ C-H bond or the aryl sp² C-H bond of toluene.

Efficient, versatile and practical palladium-catalyzed highly regioselective ortho-halogenation of azoxybenzenes

A highly efficient and practical strategy of regio-selective ortho-halogenation of azoxybenzenes with NXS in the presence of palladium catalysts has been developed in good to excellent yields.

Facile, efficient, and environmentally friendly α- and aromatic regioselective chlorination of toluene using KHSO5 and KCl under catalyst-free conditions

The nontoxic, green, safe, stable, and inexpensive reagents Oxone and KCl were employed in the non-catalyzed chlorination of toluene at room temperature.

Halocarbocyclization versus dihalogenation: substituent directed iodine(III) catalyzed halogenations

The nucleophilicity of the substituents in iodobenzene pre-catalysts have a huge impact on product selectivity in iodine(III) triggered halogenations, steering the reactivity from solely carbocyclizations towards dihalogenations. Utilizing this catalyst-dependent reactivity a diastereo- and chemoselective dihalogenation method was established allowing the conversion of structurally and electronically diverse unsaturated compounds in excellent yields.

An Environment Friendly Preparation of 3-Bromocamphor and Camphorquinone

The bromination of camphor has been carried out on a multi-gram scale by a mixture of KBr and KBrO3 in the presence of acid or with HBr/NaBr - H+ and H2O2/oxone® as the oxidant. The 3-bromocamphor is then efficiently converted to camphorquinone by an improved oxidation protocol using DMSO and sodium carbonate of tetrabutyl ammonium iodide.

A Simple Catalytic Method for the Regioselective Halogenation of Arenes

This paper describes a mild palladium-catalyzed method for the regioselective chlorination, bromination, and iodination of arene C-H bonds using N-halosuccinimides as oxidants. These transformations have been applied to a wide array of substrates and can provide products that are complementary to those obtained via conventional electrophilic aromatic substitution reactions. [reaction: see text]

Enantioselective Synthesis of (+)-Cryptophycin 52 (LY355703), a Potent Antimitotic Antitumor Agent

A highly enantioselective and convergent synthesis of cryptophycin 52 (2), an exceedingly potent cytotoxic agent, is described. Cryptophycin 52, a synthetic variant of the cryptophycin family, is currently undergoing clinical trials. The synthesis is convergent and involves assembly of three fragments, phenyl hexenal 3, d-tyrosine phosphonate 4, and protected beta-amino acid derivative 5. The synthesis of fragment 3 involves an efficient and stereocontrolled construction of both stereogenic centers at C-3 and C-4 by cleavage of a substituted tetrahydrofuran ring via an acyloxycarbenium ion intermediate. Both of these stereogenic centers were derived from optically active 4-phenylbutyrolactone, synthesized enantioselectively by Corey-Bakshi-Shibata reduction.