A Radical and An Electron Transfer Process Are Compared in Their Regioselectivities Towards A Molecule with Two Different C−I Bonds: Effect of Steric Congestion

Abstract

Steric compression in 1,4-diiodo-2,6-dimethylbenzene (2a) makes the C−I bond flanked by methyls substantially weaker (a buttressing effect) than the unhindered C−I bond. Calculations also confirm the weaker bonding interaction of the hindered C−I bond of 2a. This causes a remarkable regioselectivity toward the weaker bond in dehalogenation by stannyl radicals. Conversely, a much lower regioselectivity is found for a process −a photostimulated S RN 1 reaction with

Copper(I) Phenoxide Complexes in the Etherification of Aryl Halides

“…Dissociation of the more hindered iodide has been shown to occur after electron transfer from enolates. [22] Consistent with the absence of free or loosely bound aryl radical anions leading to free aryl radicals, the reaction of the phenligated phenoxide complex 1a with 1,4-diiodo-2,6-dimethylbenzene at 110°C in DMSO yielded the aryl phenyl ether product 8 from cleavage of the less hindered C-I bond in 86% yield, along with minor amounts of the hydrodeiodination products 10 and 11 (7 and 8% yields, respectively), as determined by GC/MS analysis of the reaction mixture and comparison to independently synthesized compounds 8-11 [Eq. (9)].…”

Copper(I) Phenoxide Complexes in the Etherification of Aryl Halides

“…Dissociation of the more hindered iodide has been shown to occur after electron transfer from enolates. [22] Consistent with the absence of free or loosely bound aryl radical anions leading to free aryl radicals, the reaction of the phen-ligated phenoxide complex 1a with 1,4-diiodo-2,6-dimethylbenzene at 110°C in DMSO yielded the aryl phenyl ether product 8 from cleavage of the less hindered C–I bond in 86% yield, along with minor amounts of the hydrodeiodination products 10 and 11 (7 and 8% yields, respectively), as determined by GC/MS analysis of the reaction mixture and comparison to independently synthesized compounds 8 – 11 [Eq. (9)].…”