Rearrangement of Rigid Cyclopropylcarbinyl Radicals: Investigation of a Reporter System for the Detection of Very Short Lived Radicals

Article abstract of DOI:10.1021/jo00307a015

The ring-opening rearrangements of the spiro-2'-yl radicals 1 and 2, the dispiro-2'-yl radical 3, and the 3',4'-dihydrospiro-2'-yl radicals 4 and 5 were investigated by the tin hydride method.At 75 deg C, the following unimolecular rate constants (k_r) were obtained: 2.1 x 10⁹ s^-1 (1), 8.6 x 10⁹ s^-1 (2), 5.3 x 10⁸ s^-1 (3), 3.0 x 10⁹ s^-1 (4), and 3.6 x 10⁹ s^-1 (5).The rate of ring opening of the 3',3'-dimethylspiro-2'-yl radical 2 is comparable to that of the bicyclo<2.1.0>pent-2-yl radical and is one of the fastest cyclopropylcarbinyl radical rearrangements currently known.