SYNTHESIS OF ALL-CARBON SPIROCYCLES BY INTRAMOLECULAR IRON-MEDIATED DIENE/OLEFIN CYCLOCOUPLING

Previous work done in the Pearson laboratory led to the success of an intramolecular double cyclization reaction using cyclohexadiene-Fe(CO)3 with pendant conjugated dienes that are attached via an amide group. Then a novel method was found for the construction of an angular triquinane skeleton by a combination of an iron-promoted tandem double ene-type cyclization followed by a ring contraction. The next logical step is to focus on using this methodology on all-carbon systems which will hopefully produce fused five-membered carbocyclic structures. Efforts were made to streamline the ene cyclization process by investigating direct reactions of alkenyl-substituted cyclohexadienes with iron pentacarbonyl, in an attempt to effect complexation and ene-coupling in one step. There were a variety of steps from the base compound that compromised the diene and its stability making it very difficult to reach the final in situ cyclization reaction. Many different routes were investigated in an effort to overcome this problem, but without success. In view of the complications encountered while attempting to synthesize a simple all-carbon spirocycle by in situ formation of the Fe-complex in the final step, efforts were directed to a model study using a different approach to construct a 4-pentenyl-substituted 2-methylcyclohexadiene-iron complex as a spirocyclization precursor. Cyclization of this material afforded a 2:1 ratio of regioisomers. Two related complexes, in which the pentenyl side chain is replaced by a butenal or hexenoic ester, respectively, were prepared via the reaction of tricarbonyl(2-methylcyclohexadienyl)iron hexafluorophosphate with the alkylzinc-copper reagent derived from methyl 4-iodobutanoate, followed by further manipulation of the ester. Unfortunately, attempted ene-cyclizations of the derived aldehyde and unsaturated ester were uniformly unsuccessful.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

Case Western Reserve University School of Graduate Studies

Year dc:date

2013

Author dc:creator

• Deslandes, Maria

Contributors dc:contributor

• Pearson, Anthony

• Chemistry

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=case1354141980

OAI identifier oai:identifier

oai:etd.ohiolink.edu:case1354141980