Bicyclo[2.2.1]heptan-2-one completely fails to undergo keto-enol tautomerism despite possessing an a — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Tautomerization to an enol requires the formation of a carbon-carbon double bond at the $\alpha$ -position. In rigid bicyclic systems, placing a double bond at the bridgehead carbon induces physically impossible angle strain, forcing an unnatural planarity. Bredt's Rule explicitly forbids the formation of a double bond at a bridgehead in small rings, thus preventing the tautomerization.