Advances in the Chemical Synthesis of Medium-Sized Cyclitols

Densely hydroxylated, medium-sized carbocycles and their analogues have long been a somewhat neglected molecular progeny for two reasons: (a) the synthesis of such expanded and functionality rich rings is quite a challenging task that remains partially unsolved and (b) the biological significance of these constructs has not yet been thoroughly appreciated. This account mainly discusses recent approaches used to deal with this rare class of carbohydrate mimics with particular emphasis being placed on annulative strategies using ring-closing metathesis, aldol-based ring closure, intramolecular nitrile oxide and nitrone cycloaddition, and the Claisen rearrangement. Less documented annulative and non-annulative procedures including free-radical cyclisation, intramolecular coupling, and ring expansion and manipulation are also considered.