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

Certain Group IVB derivatives of 1,6-methano10]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 - (or 2-) position of 1,6-methano10]annulene is ca. 35 times as reactive as the (or 1-) position of naphthalene, whereas in protiodesilylation by CF₃CO₂H/CH₃CO₂H at 27°C it is ca. 700 times the more reactive.