Electrophilic substitutions in five-membered heteroaromatic systems. Part XII. A quantitative study on the reactivities of the α- and β-positions of benzofuran and benzothiophen in electrophilic substitutions

1 January 1971

journal article
research article
Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic

p. 79-82
https://doi.org/10.1039/j29710000079

Abstract

The isomer distributions and the rates relative to those of the parent heterocyclic compounds for several electrophilic substitutions of benzo[b]furan and benzo[b]thiophen have been determined. Surprisingly, although the orientation of the substitution in the two bicyclic systems is different, the effect caused by ‘annelation’ on the reactivity of the α- and β-positions is substantially similar in the two rings: the reactivity of the α-position is always decreased by a similar factor and the reactivity of the β-position is (with two exceptions) increased, in both systems.

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