Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor(s)

Dr. Brian L. Pagenkopf

Abstract

The development of new and efficient synthetic methodologies to prepare heterocyclic compounds has received great attention over the years due to their importance in the pharmaceuticals and fine chemicals industries. Described herein are several novel syntheses of a variety of heterocycles including siloles, azaindoles, piperideines, piperidines and tetrahydropyrans.

A one-pot, two-step methodology involving Tamao’s reductive cyclization followed by Negishi cross coupling was utilized to synthesize several new series of silole-based chromophores. The property studies revealed new electropolymerized poly(thienyl-silole)s with enhanced photoefficiency for all-polymer solar cells. In addition, a new procedure is developed for the synthesis of the first dissymmetric silole tethered to amine functionality. The synthesized compounds hold great promise in the arena of biosensors and solar cell applications.

Furthermore, a novel and practical two step sequence for the preparation of C2 substituted 5-azaindoles has been reported. The synthetic sequence features a [3+2] dipolar cycloaddition between nitriles and a 3,4-cyclopropanopiperidine followed by SeO2 oxidation.

Finally, the annulation reaction between 2-alkoxy-1,1-cyclobutane diesters and imines or aldehydes gave access to highly functionalized piperidines and tetrahydropyrans, respectively. Both the synthesis of those donor-acceptor cyclobutanes and their subsequent annulations are catalyzed by catalytic Yb(OTf)3. Although known for more than two decades, this is the first use of 2-alkoxy-1,1-cyclobutane diesters in dipolar cycloadditions.

The new reactions are done under mild conditions providing the target compounds in high yields and excellent selectivity. The divergent nature and cost effectiveness of these methods make them very suitable for combinatorial applications in the pharmaceutical industry.


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