Selectivity between an Alder-ene reaction and a [2+2] cycloaddition in the intramolecular reactions of allene-tethered arynes

Substituent-dependent reactivity and selectivity in the intramolecular reactions of arynes tethered with an allene are described. With a 1,3-disubstituted allene moiety, an Alder-ene reaction of an allenic C-H bond is preferred over a [2 + 2] cycloaddition, whereas a [2 + 2] cycloaddition of the terminal pi-bond of the allene is preferred with a 1,1-disubstituted allene. With a 1,1,3-trisubstituted allene-tethered aryne, an Alder-ene reaction with an allylic C-H bond is preferred over a [2 + 2] cycloaddition.

Automated summary

This study explores the substituent-dependent reactivity and selectivity in intramolecular reactions of arynes tethered with different allene isomers. It is found that the presence of 1,3-disubstituted allene favors an Alder-ene reaction over a [2 + 2] cycloaddition, while a 1,1-disubstituted allene prefers the [2 + 2] cycloaddition. Additionally, a 1,1,3-trisubstituted allene-tethered aryne shows preference for an Alder-ene reaction over a [2 + 2] cycloaddition.