名称:
Stereochemistry of photocycloaddition of (E)-1,2-dicyano- and (Z)-1,2-diethoxyethylene to 5-substituted adamantanones
摘要:
The photocycloaddition of olefins to 5-substituted adamantanones produces two geometrically isomeric oxetanes in which the oxygen atom and the 5-substituent are in anti or syn positions. The substituent was varied from fluoro, chloro, bromo, hydroxyl, and phenyl to tert-butyl. Although the mechanisms of the reaction with electron-rich and electron-poor olefins are quite different, the product ratios are similar (approximately 60:40) in all instances. The preference of product formation from the attack on the zu face is discussed in terms of transition-state hyperconjugation.