- Controlled α-mono- and α,α-di-halogenation of alkyl sulfones using reagent-solvent halogen bonding
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The direct and selective α-mono-bromination of alkyl sulfones was achieved through base-mediated electrophilic halogenation. The appropriate combination of solvent and electrophilic bromine source was found to be critical to control the nature of the products formed, where reagent-solvent halogen bonding is proposed to control the selectivity via alteration of the effective size of the electrophilic bromine source. Conversely, the α,α-di-brominated sulfones were selectively obtained in good yields following polyhalogenation followed by selective de-halogenation during workup. Both procedures can be applied on gram scale, and the mono-halogenation was successfully extended to the fully selective α-chlorination, α-iodination and α-fluorination of alkyl sulfones.
- Poteat, Christopher M.,Lindsay, Vincent N. G.
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supporting information
p. 2912 - 2915
(2019/03/17)
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- Chemoselective mono halogenation of β-keto-sulfones using potassium halide and hydrogen peroxide; synthesis of halomethyl sulfones and dihalomethyl sulfones
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The synthesis of α-halo β-keto-sulfones using potassium halide and hydrogen peroxide as a chemoselective mono halogenation reagent and the synthesis of α,α-symmetrical and asymmetrical dihalo β-keto-sulfones and α-halo, α-alkyl and β-keto-sulfones is described. Base induced cleavage of α-halo β-keto-sulfones, α,α-dihalo β-keto-sulfones, and α-halo, α-alkyl β-keto-sulfones afforded the corresponding halomethyl sulfones, dihalomethyl sulfones and haloalkyl sulfones.
- Suryakiran,Prabhakar,Srikanth Reddy,Chinni Mahesh,Rajesh,Venkateswarlu
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p. 877 - 881
(2007/10/03)
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- A Regiospecific Reaction of Pyridazines with Vicarious Nucleophilic Substitution via Their Dicyanomethylide Derivatives
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The phenyl(or p-tolyl)sulfonylmethyl group is introduced with complete regiospecificity to the C-4 position of 3-substituted pyridazines using vicarious nucleophilic substitution of pyridazinium dicyanomethylides.
- Itoh, Takashi,Matsuya, Yuji,Nagata, Kazuhiro,Okada, Mamiko,Ohsawa, Akio
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p. 2067 - 2068
(2007/10/02)
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- Selectivity towards hydrodehalogenation and dehalo-coupling in the reduction of trichloromethyl derivatives with iron(II) chloride
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The reductive electron transfer (ET) induced on a series of RCCl3 derivatives by iron(II) chloride has been studied.The main reaction products are the homocoupling dimer, RCCl2-CCl2R, and the H/Cl substitution derivative, RCHCl2, and the majority of the compounds examined exhibit a highly selective tendency to form just one of these products.As a general rule, the RCHCl2 compound is the main product when the R group contains substituents which make further reduction of the radical to the carbanion easier and behave as ligands towards the iron(II) ion.In the other cases, the dimer RCCl2-CCl2R is the main product.A few exceptions are found, and these are discussed in view of the possible effects of the R moiety on the different possible routes for the reaction products.The presence of unsaturated derivatives, RCCl=CClR (E/Z mixture), was observed in the case of the reactions where the homocoupling product was also obtained and is ascribed, on the basis of experimental evidence, to a dehalogenation mechanism of the dimer RCCl2-CCl2R assisted by the iron(II) ion.
- Folli, Ugo,Goldoni, Francesca,Iarossi, Dario,Sbardellati, Silvia,Taddei, Ferdinando
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p. 1017 - 1020
(2007/10/02)
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- THE PREPARATION, SPECTRAL PROPERTIES, STRUCTURES, AND BASE-INDUCED CLEAVAGE REACTIONS OF SOME α-HALO-β-KETOSULFONES
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The halogenation of β-ketosulfones such as α-methylsulfonylacetophenone (1) and benzenesulfonylacetone (10) can be effected with sulfuryl chloride or pyridinium bromide perbromide.Regiochemical control can be achieved by control of stoichiometry and/or the reaction conditions.Detailed 1H and 13C nmr, and mass spectra are recorded for a series of halogenated β-ketosulfones, together with structures by X-ray crystallography for 1, 2-chloro-2-methylsulfonyl-1-phenylethanone (2), chloromethyl methyl sulfone (4), and α-chloroacetophenone (21).Results from these studies are used to suggest a reason for the difficulty associated with substitution reactions of α-halosulfones.
- Grosset, Stuart J.,Dubey, Pramod K.,Gill, Glen H.,Cameron, Stanley T.,Gardner, Patrick A.
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p. 798 - 807
(2007/10/02)
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- Synthesis of N-acyl-1,3-oxathiol-2-imines
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A facile synthesis of N-acyl-1,3-oxathiol-2-imines, 7, is reported.It comprises the reaction of O-alkyl acylcarbamothioates, 4, with 2-chloroketones in the presence of alcoholic sodium alkoxide.The resulting O-alkyl-S-substituted-N-acylcarbonimidothiates, 6, undergo cyclization with elimination of alcohol, spontaneously, or upon heating in boiling toluene to form 7.
- Kulka, Marshall
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p. 1557 - 1559
(2007/10/02)
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