Cationic Divalent Metal Sites (M = Mn, Fe, Co) Operating As Both Nitrene-Transfer Agents And Lewis Acids Toward Mediating The Synthesis Of Three- And Five-Membered N-Heterocycles

Author

Suraj Kumar Sahoo
Brent Harfmann
Lin Ai
Qiuwen Wang
Sudip Mohapatra
Amitava Choudhury, Missouri University of Science and TechnologyFollow
Pericles Stavropoulos, Missouri University of Science and TechnologyFollow

Abstract

The tripodal compounds [(TMG₃trphen)M^II-solv](PF₆)₂ (M = Mn, Fe, Co; solv = MeCN, DMF) and bipodal analogues [(TMG₂biphen)M^II(NCMe)_x](PF₆)₂ (x = 3 for Mn, Fe; x = 2 for Co) and [(TMG₂biphen)M^IICl₂] have been synthesized with ligands that feature a triaryl- or diarylmethyl-amine framework and superbasic tetramethylguanidinyl residues (TMG). The dicationic M(II) sites mediate catalytic nitrene-transfer reactions between the imidoiodinane PhI═NTs (Ts = tosyl) and a panel of styrenes in MeCN to afford aziridines and low yields of imidazolines (upon MeCN insertion) with an order of productivity that favors the bipodal over the tripodal reagents and a metal preference of Fe > Co ≥ Mn. In CH₂Cl₂, the more acidic Fe(II) sites favor formation of 2,4-diaryl-N-tosylpyrrolidines by means of an in situ (3 + 2) cycloaddition of the initially generated 2-aryl-N-tosylaziridine with residual styrene. In the presence of ketone, 1,3-oxazolidines can be formed in practicable yields, involving a single-pot cycloaddition reaction of alkene, nitrene, and ketone (2 + 1 + 2). Mechanistic studies indicate that the most productive bipodal Fe(II) site mediates stepwise addition of nitrene to olefins to generate aziridines with good retention of stereochemistry and further enables aziridine ring opening to unmask a 1,3-zwitterion that can undergo cycloaddition with dipolarophiles (MeCN, alkene, ketone) to afford five-membered N-heterocycles.

Recommended Citation

S. K. Sahoo et al., "Cationic Divalent Metal Sites (M = Mn, Fe, Co) Operating As Both Nitrene-Transfer Agents And Lewis Acids Toward Mediating The Synthesis Of Three- And Five-Membered N-Heterocycles," Inorganic Chemistry, vol. 62, no. 27, pp. 10743 - 10761, American Chemical Society, Jul 2023.

The definitive version is available at https://doi.org/10.1021/acs.inorgchem.3c01209

Department(s)

Chemistry

Comments

National Institutes of Health, Grant R15GM117508

International Standard Serial Number (ISSN)

1520-510X; 0020-1669

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2023 American Chemical Society, All rights reserved.

Publication Date

10 Jul 2023

PubMed ID

37352838