The pK,'s per hydrogen of bicyclo [3.2. l] octadiene (11, bicyclo [3.2. l Joctene (2), bicyclo [3.2. 2] nonadiene (5), and bicyclo [3.2. 2] nonatriene (6), as measured in cyclohexylamine, were 31.4,> 40.5, 34.0, and 32.0, respectively. The enhanced acidity of diene 1 corresponds
[Srinivasan, R.; Ors, Jose A.; Brown, Karen H.; Baum, Thomas; White, Lloyd S.; Rossi, Angelo R. Journal of the American Chemical Society, 1980 , vol. 102, # 16 p. 5297 - 5302]