Vinyl solvolyses are somewhat anomalous when compared with the behavior of saturated analogs. There is evidence of nucleophilic solvent involvement of alkyl-substituted vinyl substrates (m and / values are of intermediate magnitude and the effect of changes in solvent nucleophilicity at constant ionizing power is significant), but, in contrast, the carbonium ion character is high (p* is large for alkyl substitution) and added strong Society, the National Institutes of Health (Grants AI-0766 and GM-19134) and Hoffmann-La Roche, Inc., Nutley, N. J., for their support of this work. We also wish to thank Mr. W. J. Sliwinski for a sample of phenyl triflate, and Professor Z. Rappoport for constructive comments.

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Synthesis and solvolytic behavior of derivatives of the highly hindered title compounds are described, exo-Tricyclo[4.4.1.12,5]dodeca-3,7,9-trien-syn-yl tosylate (syn-18-OTs) and the corresponding perhydro derivative, syn-23-OTs, solvolyze at rates that are in reasonable agreement with those predicted by Foote-Schleyer calculations.syn-18-OTs, and its dihydro derivatives, syn-19-OTs and syn-20-OTs, give completely rearranged products on solvolysis in acetic acid and 75% dioxane, 80% acetone, and 75% dioxane, respectively (Table 2). These products can be explained by normal cationic rearrangements, probably occurring after ionization. On the other hand, anti-18-OTs and anti-23-OTs solvolyze at rates ca. 102 times slower than those predicted by Foote-Schleyer calculations. Presumably the anti derivatives of 18-OTs, 20-OTs, 23-OTs, and the tetrahydro tosylate (22-OTs) suffer steric hindrance to ionization. Product formation from anti-18-OTs (Table 3) and anti-19-OTs in acetic acid and 75% dioxane, respectively, is explained as a [3s+3s] sigmatropic shift induced by ionization, with formation of an allylic ion providing the driving force for rearrangement.

Der Einfluß der sterischen Hinderung von meta‐axialen Methyl‐Gruppen der Adamantyl‐Derivate (I)‐(VI) auf die Solvolyse wird untersucht und mit dem Solvo1yse‐Verhalten ähnlicher 2‐Norbornyl‐Derivate verglichen.

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