Stereoelectronic Effects

Stereoelectronic Effects illustrates the utility of stereoelectronic concepts using structure and reactivity of organic molecules

• An advanced textbook that provides an up-to-date overview of the field, starting from the fundamental principles

• Presents a large selection of modern examples of stereoelectronic effects in organic reactivity

• Shows practical applications of stereoelectronic effects in asymmetric catalysis, photochemical processes, bioorganic chemistry and biochemistry, inorganic and organometallic reactivity, supramolecular chemistry and materials science

Autorentext
Professor Igor V. Alabugin, Department of Chemistry and Biochemistry, Florida State University, USA
Over the last 12 years, Professor Alabugin has published a body of work dedicated to stereoelectronic effects and applied these concepts in practice to the development of new organic reactions. The wide appeal of these concepts is reflected in a large number citations for his papers on the topic (the top three papers have well over 600 citations). His expertise is in broadly defined computational and experimental organic chemistry and its applications to medicinal chemistry and materials science.

Inhalt

Acknowledgement ix

Supplementory Material x

1 Introduction 1

1.1 Stereoelectronic effects orbital interactions in control of structure and reactivity 1

1.2 Orbital interactions in theoretical chemistry 3

1.3 The birth of stereoelectronic concepts in organic chemistry 4

References 6

2 Direct Effects of Orbital Overlap on Reactivity 8

2.1 Bond formation without bond breaking: types of overlap in two?-orbital interactions 9

2.1.1 Factors controlling ?-bond overlap 12

2.2 Bond formation coupled with bond breaking 25

2.2.1 Three?-orbital interactions: stereoelectronic reasons for the preferred trajectories of intermolecular attack at a chemical bond 25

2.3 Stereoelectronics of supramolecular interactions 29

2.3.1 FMO interactions in intermolecular complexes 29

2.3.2 Expanding the palette of supramolecular interactions: from H?-bonding to Li?-, halogen, pnictogen, chalcogen and tetrel binding 30

References 36

3 Beyond Orbital Overlap: Additional Factors Important for Orbital Interactions. Classifying Delocalizing Interactions 42

3.1 Electronic count: two?]electron, one?]electron and three?]electron bonds 43

3.2 Isovalent vs. sacrificial conjugation 48

3.3 Neutral, negative, and positive hyperconjugation 49

References 52

4 Computational and Theoretical Approaches for Studies of Stereoelectronic Effects 54

4.1 Quantifying orbital interactions 54

4.2 Localized orbitals from delocalized wavefunctions 56

References 60

5 General Stereoelectronic Trends Donors, Acceptors, and Chameleons 62

5.1 Three types of delocalization: conjugation, hyperconjugation, and ?-conjugation 62

5.2 Geminal and vicinal interactions 63

5.3 Stereoelectronic main rule: antiperiplanarity 64

5.3.1 Effects of bond polarity 65

5.3.2 Polarity?-induced acceptor anisotropy 68

5.4 Scales of donor and acceptor ability of orbitals: polarization, hybridization, and orbital energy effects 68

5.4.1 Donors 68

5.4.2 Acceptors 81

5.4.3 Stereoelectronic chameleons: donors masquerading as acceptors 84

5.5 Cooperativity of stereoelectronic effects and antiperiplanar lone pair hypothesis (ALPH) theory several donors working together 91

5.6 Summary 92

References 92

6 Stereoelectronic Effects with Donor and Acceptor Separated by a Single Bond Bridge: The Broad Spectrum of Orbital Contributions to Conformational Analysis 97

6.1 /?-Interactions 99

6.1.1 Rotational barrier in ethane 99

6.1.2 Axial/equatorial equilibrium in methylcyclohexane 105

6.1.3 The gauche effect 110

6.2 /?-Interactions 113

6.2.1 Eclipsed and staggered conformations of alkenes stereoelectronic misnomers 114

6.2.2 Carbonyls 117

6.2.3 Strained bonds 121

6.3 p/?-Interactions 122

6.3.1 Primary, secondary, tertiary carbocation stabilization 122

6.3.2 Hyperconjomers of cyclohexyl cations 124

6.3.3 ?-Silicon effect and related ?-effects 124

6.4 n/?-Interactions 126

6.4.1 Anomeric effects 129

6.4.2 Reverse anomeric effect 142

6.4.3 Anomeric effects without lone pairs: beyond the n* interactions 143

6.5 n/?-Interactions 147

6.5.1 Esters and related carboxylic acid derivatives 147

6.5.2 Vinyl ethers and enamines 157

6.6 /?-Interactions 167

6.6.1 Hyperconjugation in alkynes and its relation to the absence of conjugation between two triple bonds in 1,3?-diynes 168

References 170

7 Stereoelectronic Effects with Donor and Acceptor Separated by a Vinyl Bridge 183

7.1 /* interactions 184

7.1.1 Cis?-effect: the case of two ?-acceptors 184

7.2 / interactions: allenes vs. alkenes 185

7.2.1 Neutral systems 185

7.2.2 Anions 186 7.2.3 Positive conjugation and hyperconjugation in vinyl system...