Double FLP-Alkyne Exchange Reactions: A Facile Route to Te/B Heterocycles

1-Bora-4-tellurocyclohexa-2,5-diene
undergoes sequential [4 + 2]
cycloadditions/alkyne-elimination reactions to incorporate 2 equiv
of terminal alkyne with the loss of diarylalkyne, affording access
to a series of 11 new tellurium-boron heterocycles. These alkyne exchange
reactions proceed regioselectively and can tolerate a variety of functional
groups, thus providing the potential for further derivatization. The
mechanism of the exchange reaction is confirmed by a DFT study to
involve the interaction of the Te and B with the alkyne in a frustrated
Lewis pair fashion in the transition states.