Silicon Effects. IV. Solvolysis of 1-(Pentamethyldisilanyl)-2-phenylcyclopropyl Bromide in 2,2,2-Trifluoroethanol via ?(CC)-Assisted and -Unassisted Ionization Processes

Article abstract of DOI:10.1246/bcsj.65.959

The rates of solvolysis of 1-(pentamethyldisilanyl)-, 1-trimethylsilyl-, and 1-methyl-substituted 2-phenylcyclopropyl bromides (4a, 4b, and 4c) were measured in 2,2,2-trifluoroethanol at 100 deg C: The relative rates for trans-4a, trans-4b, and trans-4c were 3.48:1.0:10.7, respectively; the trans/cis isomeric rate ratios (k^t/k^c), which were determined by competition experiments, were 2.99 for 4a and 1.70 for 4b.The solvolysis of trans-4b yielded only open allylic ethers, consistent with a ?-assisted mechanism (k_D); the trans-4a predominantly, however, gave a cyclopropyl ring-retained compound, dimethyl(2,2,2-trifluoroethoxy)silane, indicative of ?-unassisted (k_c) solvolysis.