Thermally Generated Cation Pool Enabled Condition-Controlled Synthesis of γ-Ketosulfones and β-Morpholinoketones from Methyl Ketone by α-Csp3-H Methylenation.

A modular synthetic strategy has been developed for the preparation of γ-ketosulfones and β-ketoamines from methyl ketones. Upon heating dimethyl sulfoxide (DMSO) with dichloroethane, expectedly unstable chlorine cation pools are generated, which undergo Pummerer-type rearrangement to form a reactive methyl(methylene)sulfonium ion (CH2═S+-Me). This intermediate reacts with methyl ketones in the presence of a base (amine) to afford γ-ketosulfones through C-C bond formation. Besides, sequential addition of morpholine to the in situ-generated unstable chlorine cation pools followed by a methyl ketone provides β-morpholinoketones. Remarkably, this one-pot transformation proceeds without transition metals or external oxidants, displaying excellent functional-group compatibility. In this process, dichloroethane serves as an activator of DMSO, effectively acting as a C1 donor.