C−C Bond Formation between Fischer Carbene Complexes and Allylic Alcohols by a [3,4] Sigmatropic Rearrangement Promoted by a [1,2] M(CO)5 Shift

A [1,2] M(CO) ₅ shift promotes a [3,4] sigmatropic rearrangement after the addition of allylic alcohols to Fischer alkenylcarbene complexes of tungsten or chromium in the presence of alkoxide ions. This opens a new synthetic route to the adducts 1 . The reaction is also applicable to propargylic alcohols. [M]=Mo(CO)₅, W(CO)₅.