Preparation of functionalized 3,4-pyridynes via 2-magnesiated diaryl sulfonates

The preparation of functionalized 3,4-pyridynes of type 1 as highly reactive intermediates has been achieved by the controlled elimination of readily generated 2-magnesiated diaryl sulfonates of type 2 obtained by a low temperature I/Mg- or Br/Mg-exchange starting from the corresponding halides of type 3. After trapping with furan, moderate to good yields of the desired functionalized cycloadducts of type 4 are obtained. The addition of a magnesium arylthiolate or magnesium phenylselenide to 3,4-pyridyne followed by quenching with an electrophile is also described.