Publication Date

2012-05-07

Availability

Embargoed

Embargo Period

2014-05-07

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2012-04-03

First Committee Member

Norito Takenaka

Second Committee Member

Angel Kaifer

Third Committee Member

James N. Wilson

Fourth Committee Member

John Boulos

Abstract

The development of LUMO lowering double hydrogen bond donor catalysts, 2-aminopyridinium, for the Diels-Alder reaction of nitroalkenes is described. In addition, helical chiral 2-aminopyridinium variants were identified as promising asymmetric catalysts for the intermolecular Diels-Alder of nitroalkenes, providing a first example of an enantioselective nitroalkene Diels-Alder reaction by a LUMO lowering strategy. Additionally, this LUMO lowering strategy has been successfully applied to the intramolecular nitroalkene Diels-Alder reaction to produce the first sub-stoichiometric catalytic process for the intramolecular Diels-Alder reaction of nitroalkenes. This method is capable of accessing a range of stereochemically complex [4.3.0] and [4.4.0] nitrocarbocycles in good yields and high to excellent levels of diastereoselectivity. This methodology highlights the utility of double hydrogen bond donor catalysts, 2-aminopyridinium ions, to access chemical transformations for which traditional Lewis acid catalysis has proved difficult. We have also developed a synthetic route to planar chiral 2-aminopyridinium ions, a new class of hydrogen bond donor catalysts, and found a convenient way to optically resolve them. Moreover, this catalyst was found to catalyze the nitroalkene intramolecular Diels-Alder reaction providing the adduct with excellent endo:exo selectivities and excellent yields. These planar chiral 2-aminopyridinium catalysts are a promising class of H-bond donor catalysts and in the future can be applied to other synthetically useful transformations.

Keywords

Hydrogen bond donor catalysis; Organocatalysis; Diels-Alder reactions; Intramolecular Diels-Alder Reactions; Nitroalkenes

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