Modular and Chemoselective Strategy for Accessing (Distinct) α,α‐Dihaloketones from Weinreb Amides and Dihalomethyllithiums
作者:Saad Touqeer、Raffaele Senatore、Monika Malik、Ernst Urban、Vittorio Pace
DOI:10.1002/adsc.202001106
日期:2020.11.18
The selective transfer of diversely functionalized dihalomethyllithiums (LiCHBrCl, LiCHClI, LiCHBrI, LiCHCl2, LiCHBr2, LiCHFI) to Weinreb amides for preparing gem‐dihaloketones in one synthetic operation is reported. The capability of these amides as acylating agents and, the wide availability of dihalomethanes as pronucleophiles, enable a straightforward route to the title compounds under full chemocontrol
However, when the aqueous solution contained NaOH, two α-mono-halide ketone molecules had a special dimer condensation. The reaction mechanisms were explored by conducting GC-MS, EPR, and CV with DFT calculations. These revealed that in situ generation of a halogen radical initiated electrocatalytic halogenation, while the dimer condensation involved a hydroxyl radical-mediated C1 fragment elimination.