Ring strain effects in enyne-allene thermolysis: Switch from the Myers-Saito reaction to the C2-C6 biradical cyclization

Article abstract of DOI:10.1016/S0040-4039(97)01393-2

The mode of the thermal cyclization of enyne-allenes 1 depends on ring strain effects: when the ene functionality is part of a benzene, cyclohexene or cycloheptene ring the novel C²-C⁶ biradical cyclization is observed, while when it is part of a cyclopentene ring the Myers-Saito cycloaromatization is registered.