Towards the synthesis of a homochiral bis(dipyrromethene).
Date
2006
Authors
Beshara, Cory S.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
With the advent of helical metal complexes involving linear tetra-pyrroles known as bis(dipyrromethene)s, the Thompson laboratory has been interested in a stereo-controlled self-assembly of diastereomerically enriched helicates. The following chapters illustrate efforts geared toward the diastereoselective formation of bis(dipyrromethene) helicates and a few projects of opportunity that arose as a result of the exploration of suitable homochiral pyrroles required to synthesize stereochemically enriched bis(dipyrromethene) metal complexes.
The synthesis of a homochiral pyrrole as a precursor in the synthesis of a homochiral bis(dipyrromethene) for the purposes of stereocontroled helicate formation was very important. In addition to the required synthesis of a homochiral pyrrole it was desired that the stereogenic center contain a useful appendage in order to provide a useful handle for derivatization. Thus, it was decided that the useful appendage suitable for the derivation of the homochiral pyrrole, and consequently the future bis(dipyrromethene) ligand, would be a hydroxyl group. The chemistry involved in the synthesis of a homochiral bis(dipyrromethene) ligand was thought to be incompatible with the hydroxyl functional group that was adjacent to the pyrrole ring due to the increased lability (under the required acidic conditions) of any "leaving group" that is influenced by the heterocyclic lone pair. Literature methods were employed in an attempt to combat the effect of the nitrogen lone pair and the results are described.
New methods involving the synthesis of bis(dipyrromethene)s from dipyrrinone architectures became of interest and this became a small project of opportunity. As well, the beta-acylation of pyrrole, involving mixed phosphoryl anhydrides, was explored and a successful method was devised to construct dipyrryl ketones. To complete the list of projects, a student exchange was undertaken and a preliminary method explored towards the alpha-acyloxylation of carbonyl compounds.
Thesis (Ph.D.)--Dalhousie University (Canada), 2006.
The synthesis of a homochiral pyrrole as a precursor in the synthesis of a homochiral bis(dipyrromethene) for the purposes of stereocontroled helicate formation was very important. In addition to the required synthesis of a homochiral pyrrole it was desired that the stereogenic center contain a useful appendage in order to provide a useful handle for derivatization. Thus, it was decided that the useful appendage suitable for the derivation of the homochiral pyrrole, and consequently the future bis(dipyrromethene) ligand, would be a hydroxyl group. The chemistry involved in the synthesis of a homochiral bis(dipyrromethene) ligand was thought to be incompatible with the hydroxyl functional group that was adjacent to the pyrrole ring due to the increased lability (under the required acidic conditions) of any "leaving group" that is influenced by the heterocyclic lone pair. Literature methods were employed in an attempt to combat the effect of the nitrogen lone pair and the results are described.
New methods involving the synthesis of bis(dipyrromethene)s from dipyrrinone architectures became of interest and this became a small project of opportunity. As well, the beta-acylation of pyrrole, involving mixed phosphoryl anhydrides, was explored and a successful method was devised to construct dipyrryl ketones. To complete the list of projects, a student exchange was undertaken and a preliminary method explored towards the alpha-acyloxylation of carbonyl compounds.
Thesis (Ph.D.)--Dalhousie University (Canada), 2006.
Keywords
Chemistry, Organic.