Display of Rich Reactivities of Endo- and Exocyclic Unsaturated Sugars that Parallel the Native Sugars

Unsaturated monosaccharides expand the scope of reactivities in a sugar, directly leading to the development of newer methodologies, molecular structures and functional entities. The unsaturation as a reactive moiety can either be within the molecule, namely, endocyclic, or as a pendant moiety around the molecule, namely, exocyclic. One carbon homologations aided by reactions at the unsaturated moiety expand the molecular structures in both endo- and exocyclic sugars and lead to structures that are largely hitherto unknown. Molecular shifts and rearrangements permit interchanging the reactivities from one carbon to the other in unsaturated sugars. Activations of exocyclic unsaturated sugars also find newer possibilities to reactions central to the sugar chemistry, namely, the glycosylations. The personal reflections result from a couple of decades of explorations that traverse through the unsaturated sugars from different vantage points.

Automated summary

Unsaturated monosaccharides expand the reactivity scope in sugars, leading to new methodologies, molecular structures, and functional entities. Endocyclic or exocyclic unsaturation as reactive moieties can lead to largely unknown structures through one carbon homologations. Molecular shifts and rearrangements allow interchanging reactivities from one carbon to another in unsaturated sugars, with activations of exocyclic unsaturated sugars offering newer possibilities to sugar chemistry reactions. Personal reflections stem from decades of explorations in unsaturated sugars from varied perspectives.