NOTE: Important charges and non-bonding electrons are shown throughout the animation except during the transition state phase.
Click the structures and reaction black arrows in sequence to view the 3D models and animations respectively
The reaction proceeds via an abstraction of iodine by a trimethyltin radical. The chain can then twist into a position to cyclise. The endo cyclisation to form the seven-membered ring is the minor reaction pathway. The abstraction of hydrogen from trimethyltinhydride by the cycloheptyl radical to form the endo product is not shown.