SYNTHETIC AND QUANTUM-CHEMICAL EXPLORATION OF THE SELECTIVITY OF DONOR/ACCEPTOR-SUBSTITUTED METALLOCARBENOIDS Öffentlichkeit

Abstract

Transient metallocarbenoids have become versatile intermediates for organic synthesis.
Although a variety of applications have already been described, the broad spectrum of
reactions displayed by these intermediates has led to an enormous growth in research
efforts in later years. The donor/acceptor-substituted carbenoids, derived from aryl- and
vinyldiazoacetates, are particularly stabilized and can effect highly stereo- and
chemoselective transformations. In this work, factors controlling the selectivity of these
species have been studied.
The rational syntheses of novel mixed-ligand dirhodium carboxylate catalysts of well-
defined structure are described herein. The method can be used to generate several unique
paddlewheel structures. A new class of chiral dirhodium tetracarboxylate catalysts has
also been designed, that show considerable promise for asymmetric induction in
carbenoid chemistry.
The selectivity of donor/acceptor-substituted rhodium carbenoids has been studied by
Density Functional calculations. The calculations have demonstrated why these
carbenoids are more selective than traditional carbenoid systems. A new model for the
prediction of stereochemistry in intermolecular C-H insertions was also developed from
these studies. The details of the mechanism of the combined C-H activation/Cope
rearrangement have also been described, based on extensive studies of the potential
energy surfaces.
The influence of metals, other than dirhodium complexes, on the selectivity and
reactivity of donor/acceptor-substituted carbenoids has been studied. It was found that a
new family of electron-deficient ruthenium(I) carbonyl carboxylates and silver salts
greatly enhance vinylogous reactivity of their corresponding vinylcarbenoid
intermediates. Heterobimetallic bismuth-rhodium carboxylate complexes were also
shown to be effective catalysts for carbenoid transformations, although they were much
less reactive than dirhodium catalysts. Comparative studies with analogous dirhodium
complexes revealed that, axial coordination to the dirhodium catalysts during the catalytic
cycle for carbenoid reactions, may greatly influence the reactivity.
A convenient and practical method for selective cross-dimerization of two diazo
compounds has been developed. A variety of fumarates are available through this
chemistry. The selectivity of the reaction was shown to rely on the preferred formation of
donor/acceptor-substituted carbenoids during the catalytic cycle. Underlying control
elements that determine the feasibility of cross-dimerization reactions were identified.

Table of Contents

Table of Contents

Chapter 1 Elements of Chiral Catalyst Design Based on the Rh(II)-Carboxylate Paddlewheel Scaffold 1

1.1 Introduction............................................................................................................ 1

1.2 Results and Discussion......................................................................................... 24

1.2.1 Mixed Ligand Dirhodium Carboxylates.......................................................... 24

1.2.2 Design of a Novel Family of Chiral Dirhodium Tetracarboxylates.................. 36

1.3 Conclusions............................................................................................................. 44

1.4 Experimental Section............................................................................................... 45

1.4.1 General Considerations.................................................................................... 45

1.5.2 Procedures and Characterization Data............................................................. 46

References..................................................................................................................... 59

Chapter 2 Density Functional Studies on the Selectivity of Donor/Acceptor-Substituted Rhodium Carbenoids 68

2.1 Introduction............................................................................................................. 68

2.2 Results And Discussion........................................................................................... 81

2.2.1 Selectivity of Rhodium Carbenoids................................................................. 81

2.2.2 Cyclopropenation Chemistry.......................................................................... 103

2.2.3 The Combined C-H Activation/Cope Rearrangement................................... 105

2.3 Conclusions........................................................................................................... 126

2.4 Experimental Section............................................................................................. 128

2.4.1 General Considerations.................................................................................. 128

2.4.2 Basis Sets and Pseudopotentials.................................................................... 129

2.4.3 Calculated Properties and Geometries........................................................... 131

2.4.4 Single Point Energy Calculations................................................................... 189

References................................................................................................................... 191

Chapter 3 Influence of Ru(I)- and Ag(I)-Catalysts on The Vinylogous versus Carbenoid Reactivity of Transient Metallovinylcarbenoids................................................................................................... 197

3.1 Introduction........................................................................................................... 197

3.2 Results And Discussion......................................................................................... 204

3.2.1 Electron-Deficient Ru(I) Carbonyl Carboxylates........................................... 204

3.2.2 Silver(I)-Catalyzed Reactions of Vinyldiazoacetates.................................... 210

3.3 Conclusions........................................................................................................... 230

3.4 Experimental Section............................................................................................. 231

3.4.1 General Considerations.................................................................................. 231

3.4.2 Procedures and Characterization Data........................................................... 232

3.4.3 General Computational Considerations.......................................................... 256

3.4.4 Calculated Structures and Properties............................................................. 257

3.4.5 Single Point Energy Calculations................................................................... 268

References........................................................................................................................269

Chapter 4 Bismuth-Rhodium Paddlewheel Carboxylates as Catalysts for Metallo-carbenoid Transformations 274

4.1 Introduction........................................................................................................... 274

4.2 Results And Discussion......................................................................................... 279

4.2.1 Catalytic Activity: Cyclopropanation Chemistry........................................... 279

4.2.2 Reactivity....................................................................................................... 282

4.2.3 Electronic Effects........................................................................................... 283

4.2.4 C-H Insertion Chemistry............................................................................... 286

4.2.5 Vinylogous Reactivity.................................................................................... 288

4.2.6 Density functional studies.............................................................................. 289

4.4 Conclusions........................................................................................................... 299

4.5 Experimental Section............................................................................................. 300

4.5.1 General Considerations for Synthetic Studies............................................... 300

4.5.2 Procedures and Characterization Data........................................................... 301

4.5.3 General Considerations for Computational Studies....................................... 308

4.5.4 Calculated Properties and Geometries........................................................... 312

4.5.5 Single Point Energy Calculations................................................................... 337

References....................................................................................................................... 338

Chapter 5 On The Rhodium(II)-Catalyzed Dimerization of Diazo Compounds......... 346

5.1 Introduction........................................................................................................... 346

5.2 Results And Discussion......................................................................................... 356

5.2.1 Synthetic Studies............................................................................................ 356

5.2.3 Mechanistic Studies........................................................................................ 363

5.3 Conclusions........................................................................................................... 376

5.4 Experimental Section............................................................................................. 377

5.4.1 General Synthetic Considerations.................................................................. 377

5.4.2 Procedures And Characterization Data.......................................................... 378

5.5.3 General Considerations for Computational Studies....................................... 394

5.5.4 Calculated Properties and Geometries........................................................... 395

References................................................................................................................... 411

Appendix ANMR Spectral Data for Representative Compounds...............................416

Appendix BX-Ray Crystallographic Data...................................................................422

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School	Laney Graduate School
Department	Chemistry
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Chemistry, Organic
Stichwort	catalysis rhodium carbenoids Metallocarbenoids DFT calculations
Committee Chair / Thesis Advisor	Davies, Huw, Emory University
Committee Members	Menger, Fred M, Emory University Padwa, Albert, Emory University

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