Author ORCID Identifier

https://orcid.org/0000-0002-8555-8956

Date of Award

Spring 4-19-2023

Document Type

Thesis (Ph.D.)

Department or Program

Chemistry

First Advisor

David S. Glueck

Abstract

Methylation of P-stereogenic phosphiranes Mes*PCH2CH(R) (Mes* = 2,4,6-(t-Bu)3C6H2, R = Me, Ph) with MeOTf gave P-stereogenic phosphiranium cations; [Mes*P(Me)CH2CH(Ph)][OTf] underwent syn-anti isomerization via P-epimerization. Mechanistic studies suggested ring opening gave a hyperconjugation-stabilized carbocation in which pyramidal inversion at P was promoted by s-interaction with the pendant cation. Attempted phosphirane protonation with HOTf resulted in ring opening and C-H activation of an o-t-Bu group to give phospholanium cations. Treatment of [Mes*P(Me)CH2CH(Ph)][OTf] with LiPPh2 gave bis(phosphino)ethanes. Copper- catalyzed P-alkylation of the secondary phosphine PHPh(Mes*) with benzyl bromides gave P-stereogenic tertiary phosphines with a supermesityl substituent.

Original Citation

Tipker, R. M.; Muldoon, J. A.; Pham, D. H.; Varga, B. R.; Hughes, R. P.; Glueck, D. S.; Balaich, G. J.; Rheingold, A. L. Configurational Lability at Tetrahedral Phosphorus: syn/anti-Isomerization of a P-Stereogenic Phosphiranium Cation by Intramolecular Epimerization at Phosphorus. Angewandte Chemie International Edition 2022, 61, e202110753.

Gallant, S. K.; Tipker, R. M.; Glueck, D. S. Copper-Catalyzed Asymmetric Alkylation of Secondary Phosphines via Rapid Pyramidal Inversion in P-Stereogenic Cu–Phosphido Intermediates. Organometallics 2022, 41, 1721-1730.

Tipker, R. M.; Muldoon, J. A.; Jo, J.; Connors, C. S.; Varga, B. R.; Hughes, R. P.; Glueck, D. S. Protonation of P-Stereogenic Phosphiranes: Phospholane Formation via Ring Opening and C–H Activation. ACS Omega 2023, 8, 12565-12572.

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