Gupta, Sharad
(2009)
Expanding the complexity and functional diversity of bis-amino acid building blocks.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
We are developing a unique approach to the synthesis of macromolecules with programmable shape. These scaffolds are assembled from stereochemically pure orthogonally protected bis-amino acids that are interconnected by two amide bonds. This ladder-like arrangement restricts the conformational flexibility of bis-amino acids to a large extent which in turn drastically reduces the number of allowed conformations for an oligomer. As a result, significantly lesser computing power is needed for the final three-dimensional structure prediction. Several stereochemically pure bis-amino acid monomers have been synthesized by our research group and incorporated into a number of homo- and hetero-oligomers.In this dissertation we present the synthesis of a new pipecolic acid-based bis-amino acid building block pip5(2S5S). Assembly of this monomer into a short spiroladder oligomer utilizing solid-phase synthesis followed by in situ activation by dicyclohexylcarbodiimide and N-hydroxysuccinimide has been demonstrated. The structure of the oligomer was determined in aqueous solution using two-dimensional NMR. We report improved conditions for rapidly and simultaneously closing multiple diketopiperazines on solid support. These new conditions involve either heating of a suspension of solid supported amino-tetrafluoropropyl esters in acetic acid/triethylamine catalyst solution in a microwave oven or continuous flow of catalyst solution through the resin, heated in a special flow cell apparatus.Finally, the synthesis of the first functionalized bis-amino acid monomer proAc(2S3S4R) that carries an acetyl side chain is presented. This monomer was incorporated into a short oligomer and the solution phase structure was determined using two-dimensional nuclear magnetic resonance. The solution structure confirmed the intended connectivity and stereochemistry of the oligomer. This first functionalized bis-amino acid represents a milestone towards functionalized bis-peptide nanostructures for catalytic, molecular recognition and nanotechnology applications.
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| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
30 September 2009 |
| Date Type: |
Completion |
| Defense Date: |
13 July 2009 |
| Approval Date: |
30 September 2009 |
| Submission Date: |
8 July 2009 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
bis-amino acids; diketopiperazine; foldamers; peptides |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-07082009-204223/, etd-07082009-204223 |
| Date Deposited: |
10 Nov 2011 19:50 |
| Last Modified: |
15 Nov 2016 13:45 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8309 |
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