REARRANGEMENTS OF TRICYCLO[3.2.1.1(2,4)]NON-6-YL, TRICYCLO[4.2.1.1(2,5)]DEC-3-YL, AND TRICYCLO[4.2.2.1(2,5)]UNDEC-3-YL CATIONS

The tricyclic ketones 5, 9, 13, and 24 were prepared by modified or novel routes. The corresponding tosylhydrazones 10, 11, 14, and 25 were photolyzed in 0.5 N NaOH (NaOD) to generate the title cations 2, 15-17, and 28, respectively, by way of diazonium precursors. The distribution of deuterium labels revealed rapid degenerate Wagner-Meerwein rearrangements of 2 and 28 contrasting the unsymmetrical behavior of the parent bicyclo[3.2.l]oct-6-yl cation (1). The virtually irreversible rearrangement of 17 to 15, on the other hand, mirrors the preferred chair conformation of 1. The results with tricyclic carbocations support our previous explanation for the exceptional reactivity of 1.