Chemistry Reference
In-Depth Information
Scheme 1.1
an attached PhICl radical (
86)
to generate (
87)
is followed by an intermolecular chlor-
ine transfer from another substrate to generate its attached radical.
However, because there is only a stoichiometric amount of the chlorinating agent,
side reactions mean that some substrate is left unchlorinated. Also, the attached
PhICl
2
reagent must be made by adding Cl
2
to the easily produced PhI ester. To better
achieve the same results, using chlorine transfer from an external radical to generate
the attached PhICl radical, we employed a process we called a Radical Relay Mechan-
ism [157] (Scheme 1.2). Here an external PhICl radical transfers its chlorine atom to
the iodophenyl ester group attached to the substrate, and then the intramolecular hy-
drogen atom abstraction occurs. Thus we can use a slight excess of the PhICl
2
reagent
to complete the process, and there is no need to add Cl
2
to the attached iodophenyl
group, which acts as a template to steer the chlorinations.
