Heterocyclic fused spirocyclic

Fused heterocyclic tertiary enaminones were later reported to similarly give the corresponding isoxazoles and pyrazoles188 (equation 131). The products of the Anand reaction would be the result of nucleophilic attack at the a-carbon of the enaminone followed by spirocyclization and ring opening. His observations are in clear contrast to the results of Dannhardt and coworkers who have recently189 used the closely related... 

A large number of polycyclic heterocycles containing two or more six-membered rings that share two or more carbon atoms are known. For the majority of these systems, only one of the six-membered rings contains the heteroatoms and the other rings are fused carbocyclic rings such as cyclohexane, benzene, naphthalene, and, in rare examples, anthracene. Systems in which more than one of the six-membered rings contain heteroatoms are also briefly discussed these include spirocyclic compounds and substituted naphthalenes. 

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