Direct Observation of Acyl Anion Equivalents by Carbon-13 Fourier Transform Nuclear Magnetic Resonance

Article abstract of DOI:10.1021/jo01312a027

The vinyl anions derived from 2,3-dihydrofuran, 2,3-dihydro-4H-pyran, and ethoxyethene have been examined by carbon-13 FT NMR.The vinyl C-H coupling constants (¹J_13C-1H) have been measured for the ethers and the anions.Observation of vinyl anions derived from vinyl ethers is readily accomplished with carbon-13 NMR.While all carbon resonances are shifted upon formation of the anion the most obvious effect is the large (56-61 ppm) downfield shift of the vinyl carbon bonded to lithium.In no case was allylic deprotonation observed under the reactions conditions.