Applications of Tetramethyl-Guanidine Supported Cationic Transition Metal Sites Towards C─n Bond Construction Methodologies and [3+2] Cycloaddition Reactions

Author

Suraj Kumar Sahoo, Missouri University of Science and Technology

Keywords and Phrases

C-H activation; Cationic metal compounds; Lewis-acid activity; N-heterocycles; Nitrene transfer catalysis; Tetramethylguanidinyl ligands

Abstract

"We present a family of divalent cationic bipodal and tripodal M(II) reagents (M = Mn, Fe, Co) supported by superbasic tetramethyl-guanidinyl (TMG) residue framework with applications towards C─N bond construction methodologies. These cationic reagents possess unique characteristics since their enhanced Lewis acidity facilitates in situ elaboration of the primary nitrene-transfer product (aziridine). Indeed, further aziridine-ring opening and cycloaddition of several dipolarophiles (nitriles, alkenes, ketones) permits the three-component synthesis of valuable five-membered N-heterocycles, commonly found in pharmaceuticals and agrochemicals.

We undertake a more systematic study to unravel parameters that make certain divalent metal sites more suitable as catalysts for the in-situ synthesis of five-membered N-heterocycles and explore catalytic protocols that permit formation of certain N-heterocycles as the sole product. Mechanistic studies reveal a stepwise addition of nitrene to olefins at the Fe(II) site to generate aziridines with good retention of stereochemistry, and subsequently effecting aziridine ring opening to that can undergo cycloaddition with dipolarophiles to afford five-membered N-heterocycles.

This study was further extended to cationic bipodal Cu(I) reagents supported by similar guanidinyl residue framework to achieve nitrene-transfer from PhI═NR sources to a wide variety of aliphatic hydrocarbons (C–H amination) and olefins (aziridination) and initial Hammett plots show that the reaction undergoes stepwise H-abstraction followed by C-N bond formation"-- Abstract, p. iv

Advisor(s)

Stavropoulos, Pericles

Committee Member(s)

Choudhury, Amitava
Sotiriou-Leventis, Lia
Mormile, Melanie R.
Reddy, Prakash, -2024

Department(s)

Chemistry

Degree Name

Ph. D. in Chemistry

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2025

Pagination

xiii, 198 pages

Note about bibliography

Includes_bibliographical_references_(pages 185-197)

Rights

©2023 Suraj Kumar Sahoo , All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12489

Recommended Citation

Sahoo, Suraj Kumar, "Applications of Tetramethyl-Guanidine Supported Cationic Transition Metal Sites Towards C─n Bond Construction Methodologies and [3+2] Cycloaddition Reactions" (2025). Doctoral Dissertations. 3388.
https://scholarsmine.mst.edu/doctoral_dissertations/3388