294662-87-6Relevant academic research and scientific papers
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
Branchi, Barbara,Galli, Carlo,Gentili, Patrizia,Marinelli, Manuela,Mencarelli, Paolo
, p. 2663 - 2668 (2000)
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 the enolate ion of a ketone - which requires the conversion of 2a into a radical anion. A calculation of the BDE of the C-I bond for aa ArI·- system is offered. Finally, the hindered awl radical intermediate resulting from cleavage of the weaker C-I bond of 2a·- shows a modest but detectable discrimination between reduction or substitution, this once again being due to the steric congestion.
