In Situ Generation of Alkyl–λ³–Iodanes as Soft and Highly Reactive Electrophiles

Hypervalent iodine compounds have found various applications in organic chemistry and related research fields. Compared with aryl-, alkynyl-, and alkenyl-substituted iodanes and iodonium salts, alkyl–λ³–iodanes have been much less studied due to their infamous instability and the lack of convenient methods for their generation. Herein, it is reported that the reaction between a tetraalkylsilane and iodine tris(trifluoroacetate) at low temperature cleanly generates the corresponding alkyl–λ³–iodane in commonly used chlorinated solvents. The in situ-generated alkyl–λ³–iodanes are reasonably stable at low temperature, and Me–λ³–iodane serves as a soft and highly electrophilic methylating agent for tertiary sulfonamides. This alkylative activation of tertiary sulfonamides provides reactive sulfonyl ammonium intermediates that can achieve transamidation and fluorination reactions, thus demonstrating the synthetic utility of the in situ-generated alkyl–λ³–iodane.