Strategies for oxidative synthesis of -triflyl sulfoximines.

The oxidation of various structurally different -trifluoromethylthio sulfoximines was investigated using different oxidizing agents and conditions. Mono- and disubstituted phenyl methyl and phenyl cyclopropyl -trifluoromethylthio sulfoximines were oxidized with NaOCl·5HO in water, while sterically hindered substrates bearing bulkier alkyl chains or two phenyl rings required the addition of MeCN to the reaction mixture. Chloro-, bromo-, and cyano-substituted substrates, as well as substrates bearing the benzyl groups, required a completely different approach using -CPBA in DCM. Each method was tested on a gram-scale, with almost no difference in yield or reaction profile. The methods were also tested on -tolylthio sulfoximine where successful oxidation to the corresponding sulfone derivative was observed. Finally, the -triflyl sulfoximines acquired in the oxidations were examined in terms of stability and reactivity in Suzuki-Miyaura and Sonogashira coupling reactions, as well as many others. The selective mono- and dinitration of 4-methoxyphenyl -triflyl sulfoximine was demonstrated by using nitric and sulfuric acid. -triflyl sulfoximines were found to be stable in concentrated aqueous NaOH and HCl solutions and at elevated temperatures.