Date of Award


Publication Type

Doctoral Thesis

Degree Name



Chemistry and Biochemistry

First Advisor

Green, J.




The Nazarov cyclization reaction has been used as an effective method to synthesize cyclopentanones. While 6-membered ring systems can be available by way of the homo Nazarov variant, 7-membered ring formation involving a Nazarov-type reaction is very rare, and completely unknown thermally. Using the established concept of the ability of the alkyne-Co2(CO)6 moiety to enable the formation of -carbonyl cations and the good stability of this generated cation, 7-membered ring formation via the vinylogous Nazarov reaction with electron deficient enones has been investigated. The desired aryl substituted enyone-Co2(CO)6 complex precursors for the cyclization reaction have been prepared from commercially available starting materials, using a series of reactions that include Sonogashira cross-coupling, desilylation, organolithium reactions with aldehydes, oxidation and complexation reactions. The treatment of the respective complex precursors, using SnCl4 as a suitable Lewis acid, successfully generated cycloheptynone-Co2(CO)6 complexes. The substitution effects have been examined, showing that introducing a bulky group at the alpha-position to the carbonyl enhances the cyclization efficiency by enabling the desired s-trans/s-trans conformation. On the other hand, beta-substituting with an R group other than H atom reduces the reaction rate and allows formation of the desired 7-membered ring only in very low yield. Preparation of appropriate dienynone-Co2(CO)6 complex substrates allowed expansion of the reaction scope to non-aromatic starting materials. Successful reductive decomplexation of the cycloheptynone-Co2(CO)6 unit also was demonstrated.