Stereoelectronic effects in the deprotonation of arylalkyl radical cations: meso-ethylanthracenes

Article abstract of DOI:10.1021/ja00162a043

In contrast to meso-methylanthracenes, which are oxidized by one-electron oxidants to hydroxymethyl derivatives, meso-ethylanthracenes such as 9,10-diethylanthracene (DEA) undergo a facile chemical or biochemical oxidative elimination of ethylene to yield an anthrone. No trace of ethyl side chain oxidation to a 1-hydroxyethyl derivative is observed. The rationale for this dramatic selection between methyl and ethyl reactivity is a stereoelectronic effect on radical cation deprotonation. 9-Ethyl-10-methylanthracene (EMA) undergoes both oxidative pathways, but the competition between the two pathways is mediated by water. This effect is attributed to the intervention of a water cluster in the deprotonation reaction.