Date of Award

6-2011

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Wei Zhang

Second Advisor

Marianna Torok

Third Advisor

Jonathan Rochford

Abstract

Green chemistry integrates the environmental benign and sustainable protocols for chemical research and production. Recently, many synthetic approaches with green chemistry aspects have been developed. For example, microwave irradiation applies energy directly to solvents and reactants, which significantly reduces the reaction time. Multicomponent reactions (MCRs) incorporate reactants for the rapid construction of complex molecules. Fluorous solid-phase extraction (F-SPE) is a chromatography-free purification method that reduces the amount of solvent used.

These new techniques have been applied to construct a series of heterocyclic molecules: bridged oxazabicycle, which has been found to be an example of a bicycle-based photochromic colorant and the ideal substrate to study the molecular switch; pyranopyrazole, which is considered to be an important pharmaceutical scaffold; and 1,4-dihydropyridine, which has been reported as a multi-drug resistance (MDR) reversing agent.

A combination of advanced green techniques is applied to our perfluorooctanesulfonyl benzaldehyde-based synthesis to assemble a series of heterocyclic scaffolds. Perfluorooctanesulfonyl (C8F17O2SO-) protected benzaldehyde is used as a limiting reagent for MCRs to form the condensed product. MCRs are performed under microwave irradiation to quickly assemble the heterocyclic skeleton, and microwave-assisted Suzuki-Miyaura cross-coupling reactions remove the fluorous tag and introduce biaryl functionality to the heterocyclic compounds. The intermediates are isolated from the reaction mixtures by F-SPE. Our synthetic routes demonstrate the green chemistry approaches of microwave-assisted fast reactions; high atom economic MCRs; and chromatography-free F-SPE that could significantly improve the synthetic efficiency.

Comments

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