Alt Title

Synthesis and activity of ruthenium carbene complexes as reusable catalyst for olefin metathesis (part 1). carbamoylsilane synthesis

Publication Date

2005

Document Type

Dissertation/Thesis

First Advisor

Cunico, Robert F.||Yao, Qingwei (Professor of chemistry)

Degree Name

Ph.D. (Doctor of Philosophy)

Department

Department of Chemistry and Biochemistry

LCSH

Metathesis (Chemistry)||Ruthenium compounds

Abstract

In the past decade, olefin metathesis catalysts based on transition metal alkylidene complexes have become a very powerful tool for carbon-carbon bond forming reactions. Olefin Metathesis allows for the catalytic cleavage and formation of C-C multiple bonds under mild conditions in the presence of various functional groups. Olefin metathesis can be mediated by a number of transition metals, but one of the most widely used catalysts is the Grubbs ruthenium alkylidenes. They are highly efficient catalyst precursors, moderately sensitive to moisture and air, and very tolerant of many different organic functional groups. However, these catalysts are prepared by using expensive ruthenium alkylidene complexes, which are rarely reusable after their first use, and often possess serious problems during purification. Given the growing importance of olefin metathesis in organic synthesis, it is very important to find an effective method to recycle these catalysts and obtain highly pure products. A variety of homogeneous and heterogeneous polymer-supported ruthenium carbene catalysts (PCy₃)₂Ru(=CHPh)Cl₂, and (PCy₃)Ru(SIMes)(=CHPh)Cl₂ have been prepared and found to be very effective for olefin metathesis. They show comparable reactivity to their homogeneous counterparts. These catalysts are reusable, recovered inexpensively and without significant waste generation, yielding highly pure products. The second part of this dissertation reports reactivity and mechanism studies of the reaction between carbamoylsilanes and electrophilically functionalized olefins. The Si-C bond of N,N-dimethylcarbamoyl (trimethyl)silanes added regiospecifically to the C=C bond of electrophilically functionalized alkenes to afford β-silyl-β-functionalized amides. In contrast, carbonyl addition products were formed when hindered alkenic esters were used. Increased reactivity was observed when more crowded (at Si or N) carbamoylsilanes were used. Variations in carbamoylsilane structures were used to probe possible factors influencing the reaction rate.

Comments

Includes bibliographical references (pages [162]-168).

Extent

xviii, 168 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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