Atropine, $\mathrm{C}_{17} \mathrm{H}_{23} \mathrm{NO}_{3},$ is a poisonous alkaloid isolated from the leaves and roots of Atropa belladonna, the deadly nightshade. In small doses, atropine acts as a muscle relaxant; $0.5 \mathrm{ng}$ (nanogram, $10^{-9} \mathrm{g}$ ) is sufficient to cause pupil dilation. On basic hydrolysis, atropine yields tropic acid, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}\left(\mathrm{CH}_{2} \mathrm{OH}\right) \mathrm{CO}_{2} \mathrm{H},$ and tropine, $C_{8} \mathrm{H}_{15} \mathrm{NO}$. Tropine is an optically inactive alcohol that yields tropidene on dehydration with $\mathrm{H}_{2} \mathrm{SO}_{4}$. Propose a structure for atropine.
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