VINYL CATIONS .30. PREPARATION AND SOLVOLYSIS OF 1-CYCLOBUTENYL NONAFLATES - GENERATION OF STABILIZED VINYL CATION SPECIES

1-Cyclobutenyl nonaflate (16) and the series of 2- and 3-methyl- and aryl-substituted cyclobutenvl nonaflates 17, 18, 19, 21, and 22 were synthesized by treatment of either the corresponding cyclobutanones directly with nonafluorobutanesulfonic acid anhydride or using the lithium enolates (e.g., 30a, 30b) as starting compounds for a reaction with the anhydride. The solvolysis reactions of the cyclobutenyl nonaflates were studied in various solvents. All cyclobutenyl nonaflates solvolyze via a vinyl cation mechanism leading to rearranged cyclopropyl and homopropargyl compounds, the product composition being dependent upon the substituents in the 2 and 3 position. The same products as are formed in the solvolysis of the cyclobutenyl nonaflates are also found in the solvolysis reactions of cyclopropylidene methyl (11) and homopropargyl derivatives (7), pointing to the same cationic intermediates. The solvolysis products and the rates of the cyclobutenyl nonaflates are in agreement with the formation of stabilized bridged 1-cyclobutenyl cations (14, 55, 67). © 1979, American Chemical Society. All rights reserved.