NBS-mediated synthesis of β-keto sulfones from benzyl alcohols and sodium arenesulfinates
An efficient synthetic route towards the synthesis of β-keto sulfones has been developed from secondary benzyl alcohols using N-bromosuccinimide (NBS). The present protocol utilizes NBS as oxidant as well as brominating agent, readily accessible benzyl alcohols and sodium arenesulfinates as the sulfonylating reagent under mild conditions. The control experiments revealed that the reaction proceeds via oxidation of alcohol to ketone, α-bromination of ketone and nucleophilic substitution by sodium arenesulfinate. Furthermore, the efficiency of the methodology was tested with a gram scale reaction and also shown the synthetic utility.
Convenient Methods for the Preparation of Vinylic and Allylic Sulfones from Alkenes, Haloalkanes, and Aldehydes. Stereochemistry of the Conversion of Vinylic Sulfones to the Corresponding Allylic Sulfones
1- or 2-p-Tolylsulfonyl(=tosyl)-1-alkenes, vinylic sulfones, were regioselectively prepared from 1-alkenes via iodosulfonization or sulfonylmercuration and also from 1-haloalkanes by the homologation or unhomologation methods.The vinylic sulfones thus prepared were further converted to the corresponding allylic sulfones under basic conditions.The stereochemistry of this conversion was discussed.One-carbon homologated allylic sulfones were directly obtained from aldehydes in good yields by the reaction with diethyl phenylsulfonylmethylphosphonate and 1,8-diazabicycloundec-7-ene (DBU) under mild conditions.