1

This section has attempted to introduce the use of exoanomeric methylene groups as a means for the formation of more complex C-glycosides. Such species are also apparent as intermediates in the formation of C-disaccharides and will be addressed in Chapter 8. For now, let it suffice that exoanomeric methylene groups, considered within other means of C-glycoside syntheses are quite complimentary and beneficial to the general chemical knowledge surrounding C-glycosides. 1. Lopez, M. T. G. Heras,...

Contents

1 Organization of the Book 1 1.1 Definition and Nomenclature of C-Glycosides 1 1.2 O-Glycosides vs. C-Glycosides Comparisons of Physical Properties, Anomeric Effects, H-Bonding Abilities, Stabilities and Conformations 4 1.3 Naturally Occurring C-Glycosides 7 1.4 C-Glycosides as Stable Pharmacophores 10 Chapter 2. Electrophilic Substitutions 29 2.1 Anomeric Activating Groups and Stereoselectivity 29 2.2 Cyanation Reactions 30 2.2.1 Cyanation Reactions on Activated Glycosides 31 2.2.2 Cyanation...

Cn

2.2.4 Cyanation Reactions with Metallocyanide Reagents TMSCN is not the only reagent useful for the formation of cyanoglycosides. Complimentary and, perhaps, equally important is the use of aluminum reagents. As applied to pyranose sugars, Grierson, et al.,10 demonstrated that the stereochemical outcome of the cyanation reaction with diethylaluminum cyanide was temperature dependent. Thus, as shown in Scheme 2.2.11, at room temperature, a mixture of a and p isomers were formed while, at reflux,...

Tms

Where the use of Lewis acid chemistry demonstrates the utility of electrophilic substitutions in the preparation of C-disaccharides, methodologies involving nucleophiles are extremely complimentary. Already discussed in Chapter three and presented in numerous schemes throughout this chapter, sugar-derived nucleophiles provide excellent sources of C-glycosidation substrates. These observations were further exemplified by Schmidt, et al.,28 in a study illustrating the generality of anionic...

Tmsi

This book is divided into eight chapters. Each of the first seven chapters centers around a different class of reactions. The sections within each chapter define subsets of the reaction classes. For example, Chapter 2 deals extensively with electrophilic substitutions as a means of forming C-glycosides. However, each section within the chapter deals with methods used for the formation or introduction of specific groups at the C-glycosidic linkage. Chapter 8 is different from the first seven...