Henry A. Olszowy

Stereochemistry of trifluoroacetolysis and brominolysis of the cyclohexyl-tin bond

(cis- and trans-4-methyl- and 4-tert-(butylcyclohexyl)triisopropylstannanes have been synthesized and fully characterized. Trifluoroacetolysis of these compounds proceeds stereospecifically with retention of configuration at carbon. Electrophilic bromination is characterized by a fine energetic balance between inversion and retention pathways, with the former favored for the equatorial carbon-tin bonds and the latter for axial carbon-tin bonds in these triisopropylstannanes. Bromination under free-radical conditions yields a statistical mixture of the cis- and trans-4-alkylcyclohexyl bromides, a result appropriate for bromine atom transfer to a 4-alkylcyclohexyl free radical.

Some group IVB derivatives of 1,6-methano [10] annulene. Synthesis, substituent effects and reactivity

Abstract Certain Group IVB derivatives of 1,6-methano[10]annulene have been synthesised, and their 13C nuclear magnetic resonance spectra recorded and assigned, to provide a measure of the substituent effects exerted by metalloid-containing groups in this non-benzenoid aromatic system. Comparisons are made with the corresponding naphthalene and some anthracene derivatives. Protiodemetallations of a number of arylsilanes and -stannanes have been examined, and in protiodestannylation by CH3CO2H/dioxane at 27°C (an electrophilic aromatic substitution) the α- (or 2-) position of 1,6-methano[10]annulene is ca. 35 times as reactive as the α (or 1-) position of naphthalene, whereas in protiodesilylation by CF3CO2H/CH3CO2H at 27°C it is ca. 700 times the more reactive.