Iodoaryl template

We irradiated a solution of phenyliodine dichloride with the w-iodobenzoate ester 12 of 3a-cholestanol and found that C-9 chlorination occurred selectively, while no such selectivity was seen without the iodine atom on the benzoate ester [37]. Various controls established that we were not simply converting the attached iodoaryl template to its... 

More recently, we have extended ion pairing to template-directed chlorination [15]. Since in the chlorination reactions HCl is produced, we could not use carboxyl-ate anions. However, ion pairs of substrate cations with iodoaryl templates carrying sulfonate anion groups directed chlorination with reasonably good selectivity. Somewhat poorer selectivity, because of flexibility, was achieved when the template carried the cationic group and the substrate was a sulfate anion. The ion paired template shows turnover catalysis by moving on to another substrate molecule after... 

The most extensive studies we have done in geometrically directed functionalizations have involved the template directed chlorination of unactivated C-H bonds. These have been reviewed in detail [6], so only a few examples will be mentioned. The first system examined [7] involved attachment of an iodoaryl group to a steroid substrate, conversion of the iodine atom to an ICI2 group, and free radical chain chlorination. After initiation of the chain a radical was produced carrying a single chlorine on the iodine atom this chlorine then removed a hydrogen atom from the attached substrate. 

---