Expanding the scope of donor/acceptor rhodium-carbene chemistry Open Access

Wang, Yuxing (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/0g354g26p?locale=en
Published

Abstract

The reactions of donor/acceptor rhodium carbenoids have been studied extensively in the past several decades. Cyclopropanation was a major early application of rhodium carbenoid chemistry and has been widely used in both academia and the industrial world. Also, C-H insertion by rhodium carbenoids is one of the most promising methodologies for C-H functionalization. This work attempts to expand the scope of existing rhodium carbenoid methodologies as well as develop new methodologies.

The first part of this thesis describes a systematic optimization of catalyst, solvent, reaction temperature, additive, as well as reaction substrates to achieve C-H insertion of Rh(II)-stabilized carbenoids into acetals with high enantioselectivity. Eight substrates were tested under optimized conditions affording C-H insertion product in 25 - 83% yield and 87 - 94% ee. This reaction can be considered as a surrogate for the Claisen condensation.

The second part of the thesis describes the development of the combined C-H functionalization/Cope rearrangement (CHCR) and C-H insertion reaction with triazoles and dihydronaphthalene. However, the reaction scope is very limited, and only a few substrates are compatible with this transformation.

The last part of the thesis describes the development of an asymmetric transformation of propargylic alcohols with donor/acceptor-substituted carbenoids affording 2,5-dihydrofuran derivatives via tandem ylide formation/[2,3]-sigmatropic rearrangement/cycloisomerizaion using S-xylyl-BINAP(AuCl)2 and AgSbF6 as the catalysts.

Table of Contents

Chapter 1. Introduction 1

1.1 Metallocarbenoid chemistry 1

1.2 Chiral catalysts for metallocarbenoid chemistry. 4

1.3 Use of triazoles as an alternative carbene precursor. 6

References. 10

Chapter 2. Asymmetric C-H insertion of Rh(II)-stabilized carbenoids into acetals: a surrogate for the Claisen condensation 14

2.1. Introduction. 14

2.1. Results and discussion. 18

2.3. Future directions 27

2.4. Summary. 28

References. 29

Chapter 3. Combined C-H Functionalization/Cope Rearrange Reaction with Triazoles. 31

3.1 Introduction 31

3.1.1 CHCR reaction 31

3.1.2 Using triazole as a mask of donor/acceptor carbenoid 32

3.2. Results and discussion. 34

3.3. Summary. 42

References. 43

Chapter 4. Asymmetric transformations of propargyl alcohols with donor/acceptor-substituted carbenoids. 45

4.1 Introduction 45

4.2 Results and Discussion 48

4.3 Summary. 54

References. 55

Experimental Section 56

General Methods. 56

Experimental Section for Chapter 2: Asymmetric C-H insertion of Rh(II) stabilized carbenoid into acetals: a surrogate for the Claisen condensation 57

I. General procedure for C-H insertion into dioxalene. 57

II. Experimental Data 57

Experimental Section for Chapter 3: Combined C-H Functionalization/Cope Rearrangement Reaction with Triazoles. 67

I. General procedure for Combined C-H Functionalization/Cope Rearrangement Reaction with Triazoles 67

II. Experimental Data 67

Experimental Section for Chapter 4: Asymmetric transformations of propargyl alcohols with donor/acceptor-substituted carbenoids 77

I. General procedure for substituted propargyl alcohol. 77

II. General procedure for 3-silyl-substituted propargyl alcohol. 77

III. General method for the gold catalyzed reaction of propargyl alcohol and aryldiazoacetates

78

IV. Experimental Data 78 78

About this Master's Thesis

Rights statement
  • Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.
School
Department
Degree
Submission
Language
  • English
Research field
Keyword
Committee Chair / Thesis Advisor
Committee Members
Last modified

Primary PDF

Supplemental Files