ORCID

0000-0002-9765-5120

Keywords

Catalyst, Rhodium, Silane, C–H Silylation, Arylalkoxysilanes, Silane Redistribution

Abstract

This thesis is comprised of two main themes: (i) harnessing the control of redistribution-prone hydroalkoxysilanes by utilizing well-defined preformed catalysts, and (ii) protocols for intermolecular C–H silylation of hydroalkoxysilanes and unactivated arenes to access function arylalkoxysilanes. The first portion of this thesis focuses on protocols for Rh-catalyzed intermolecular C–H silylation of unactivated arenes and heteroarenes with monoalkoxysilane, HSiMe2(OEt). The silylation is catalyzed by 0.5 mol % of [RhCl(Ph-BPE)]2, derived from [Rh(coe)2Cl]2 and (S,S)-Ph-BPE, in the presence of cyclohexene as a hydrogen scavenger at 100 °C, affording the desired arylethoxydimethylsialnes up to 99% yield. The regioselectivity of the monoalkoxysilane is mainly affected by the steric bulk of the substituents on the arenes and electronics serve as an ancillary factor. A mechanistic study reveals that the mono-hydrido Rh-complex is an active catalytic intermediate that further suppresses silane redistribution. The protocol extends to double C–H silylation, affording bis(ethoxydimethylsilyl)heteroarenes up to 98% yield. The second portion of this thesis covers protocols for C–H silylation of trialkoxysilane, HSi(OEt)3, of unactivated arenes and heteroarenes. The silylations are catalyzed by 1-3 mol % of [RhCl(DTBM-MeO-BIPHEP)]2, derived from [Rh(coe)2Cl]2 and (S)-DTBM-MeO-BIPHEP, in the presence of cyclohexene at 90-120 °C. Heteroarenes were catalyzed by 1 mol % [RhCl(DTBM-MeO-BIPHEP)]2 at 90 °C, up to 99% yield. Two different setups were employed: heteroarene as the limiting reagent in a solvent (THF) and HSi(OEt)3 as the limiting reagent under neat conditions. The portionwise addition of silane often increased yields and suppressed silane redistributions. Protocols for the silylation of unactivated arenes required excess arene, higher catalyst loading, increased temperature, and four portionwise additions. This protocol was extended towards no hydrogen scavenger, monoalkoxysilane, and dialkoxysialne reactions. Redistribution studies found that using well-defined preformed catalyst reduced hydroalkoxysilane redistributions. Finally, mechanistic studies identified catalytic intermediates to help understand the difference between arene and heteroarene silylation.

Completion Date

2024

Semester

Fall

Committee Chair

Lee, Kangsang

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Chemistry

Format

PDF

Identifier

DP0029038

Language

English

Release Date

12-15-2024

Access Status

Dissertation

Campus Location

Orlando (Main) Campus

Accessibility Status

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