By functionalizing the privileged
biphenyl-2-ylphosphine with a
basic amino group at the rarely explored 3′ position, the derived
gold(I) complex possesses orthogonally positioned “push”
and “pull” forces, which enable for the first time soft
propargylic deprotonation and permit the bridging of a difference
of >26 p<i>K</i><sub>a</sub> units (in DMSO) between
a propargylic
hydrogen and a protonated tertiary aniline. The application of this
design led to efficient isomerization of alkynes into versatile 1,3-dienes
with synthetically useful scope under mild reaction conditions