Optimization of Rh2(S-TPPTTL)4 Through Ligand Diversification Pubblico

Abstract

Discovering new ways to alter the classically inert C-H bond at different positions in a molecule has proven to be a valuable method to synthesize several complex structures. Dirhodium catalysts have been shown to perform these alterations with high yield and stereoselectivity. One of the most notable catalysts with promising reactions is the Rh2(tetra-phenyl-phthalimido-tertbutyl-leucino)4 catalyst (Rh2(TPPTTL)4). This catalyst has been shown to catalyze cyclopropanations and highly stereo-specific C-H functionalizations. A key factor in dictating this catalyst’s specificity is its C4 symmetry and large steric bulk, which was chosen as a promising area for optimization. Further optimization studies of this catalyst were conducted to broaden its scope of reactions and study the structure of the catalyst’s active site. This was achieved by increasing the overall bulk of the catalyst and the steric demand close to the catalyst’s active site.

Table of Contents

1. INTRODUCTION

1.1) The Biological Relevance of Stereoselective Synthesis

Figure 1.1.1

Figure 1.1.2

1.2) Dirhodium catalysts

Figure 1.2.1

Figure 1.2.2

1.3) C-H Functionalization

Figure 1.3.1

Figure 1.3.2

1.4) The Rh2(TPPTTL)4 Catalyst

Figure 1.4.1

2) MANIPULATING THE TPPTTL LIGAND

2.1) Synthetic Scheme

Figure 2.1.1

Figure 2.1.2

Figure 2.1.3

2.2) Synthetic Steps

Figure 2.2.1

Figure 2.2.2

Figure 2.2.3

Figure 2.2.4

Figure 2.2.5

Figure 2.2.6

2.3) Preparation for Manipulation via Suzuki Coupling

Figure 2.3.1

Figure 2.3.2

2.4) Suzuki Coupling Methodology

Figure 2.4.1

Figure 2.4.2

Figure 2.4.3

Figure 2.4.4

3) CATALYST CHARACTERIZATION

3.1) NMR

Figure 3.1.1

3.2) X-ray Crystallography

Figure 3.2.1

3.3) Mass Spectrometry

Figure 3.3.1

4) ASSESSING THE SELECTIVITY OF THE TPPTTL VARIANTS

Figure 4.1.1

Figure 4.1.2

Figure 4.1.3

Figure 4.1.4

Figure 4.1.5

Figure 4.1.6

4.2) Rh2(S-p-Br-TPPTTL)4

Figure 4.2.1

Figure 4.2.2

4.3) Rh2(S-3,5-m-Br-TPPTTL)4

Figure 4.3.1

Figure 4.3.2

4.4) Rh2(S-p-^tbutyl-TPPTTL)4

Figure 4.4.1

Figure 4.4.2

4.5) Rh2(S-p-bisCF3-TPPTTL)4

Figure 4.5.1

Figure 4.5.2

4.6) Rh2(S-p-mesityl-TPPTTL)4 Catalyst

Figure 4.6.1

Figure 4.6.2

4.7) Rh2(S-3,5-m-ph-TPPTTL)4

Figure 4.7.1

Figure 4.7.2

4.8) Rh2(S-3,5-m-bisCF3-TPPTTL)4

Figure 4.8.1

Figure 4.8.2

5) CONCLUSION

6) EXPERIMENTAL

7) HPLC AND NMR DATA

8) REFERENCES

About this Honors Thesis

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School	Emory College
Department	Chemistry
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Chemistry, Organic
Parola chiave	Rhodium Catalysis
Committee Chair / Thesis Advisor	Huw Davies, Emory University
Committee Members	Manoj Thapa, Emory University Matthew Weinschenk, Emory University

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