Nucleophilic additions of [(diethoxyphosphoryl)difluoromethyl]lithium to α,β-unsaturated compounds

The presence of HMPA leads to an increase of 1,4- versus 1,2-additions of [(diethoxyphosphoryl)difluoromethyl]lithium onto α,β-unsaturated ketones and provides products of conjugated addition in moderate to good yields. In the absence of HMPA, benzylidine or alkylidine 1,3-diones, malononitriles or malonates as well as nitroalkenes and other Michael acceptors give products of 1,4-addition in good to high yields.

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► 1,2- versus 1,4-addition of the title reagent to α,β-unsaturated ketones was investigated in the presence of HMPA.
► In cyclic α,β-unsaturated ketones, addition of HMPA varies 1,2/1,4 ratio.
► Benzylidine or alkylidine 1,3-diones, malononitriles or malonates and nitroalkenes undergo conjugate addition with the title reagent.