Metal-free synthesis of N-sulfonyl imines from benzyl alcohol derivatives and iminoiodinanes via mechanochemistry

An expedient and operationally convenient mechanochemical synthesis of aryl/heteroaryl N-sulfonyl imines is reported by reacting iminoiodinanes with numerous aryl/heteroaryl benzyl alcohols in ball milling apparatus (RETSCH 400™) with three 5 mm stainless steel (ss) balls in a 5 mL stainless steel (ss) reaction jar. CHCl3 (η = 0.2-0.4 μL mg-1) was used as a liquid assisted grinding (LAG) auxiliary. This metal catalyst- and base- free synthesis with nominal amounts of solvents (as LAGs) demonstrated an efficient N-sulfonyl transfer reaction from iminoiodinanes to afford the desired compounds in moderate to good yields. Substituted N-sulfonyl imines are crucial as standalone natural product building blocks and drug intermediates as well as precursors of sulfonamides which have been involved in potential small molecule therapy in many therapeutic programs. The putative mechanisms of the transformations are discussed based on control reactions and DFT calculations.