Hindered organoboron groups in organic chemistry. 23. The interactions of dimesitylboron stabilised carbanions with aromatic ketones and aldehydes to give alkenes

Article abstract of DOI:10.1016/S0040-4020(01)87981-3

Dimesitylboron stabilised carbanions react with diarylketones to give the corresponding alkenes in mild conditions with good yields. Reactions with aromatic aldehydes are more complex, but in all cases E-alkenes are available in good yields by trapping the intermediates with chlorotrimethylsilane followed by treatment with aq. HF/CH₃CN. Treatment of the same intermediates with trifluoroacetic anhydride gives mainly the Z-alkenes. The design and mechanisms of these important processes are considered.