Synthesis of 3‑Substituted 3‑Bromo-1-phenylallenes from Alkynylcycloheptatrienes

A new
method has been developed for the preparation of 3-bromo-1-phenylallenes
from 7-alkynylcycloheptatrienes and N-bromosuccinimide.
Trisubstituted bromoallenes were obtained at room temperature in moderate
to excellent yields. Functionalization of the carbon–bromine
bond via Pd- or Cu-catalyzed cross-coupling reactions easily provided
substituted allenes.