ABSTRACT
The classic ionic methods for the removal of an unwanted hydroxyl group are summarized in detail in the book by Larock [6]. One method involves-for primary and unhindered secondary alcohols-the synthesis of the corresponding mesylates or tosylates. These compounds are prepared readily and then transformed into the corresponding deoxy compounds by reduction [7]. Alternatively, introduction of a thiolate or halogen by a nucleophilic reaction can also be used. These compounds can then be readily desulfurized or dehalogenated (Scheme 1). Tertiary alcohols present no problem either, because a
dehydration-reduction sequence leads to the required deoxy compound in high yield [7]. However, deoxygenation of secondary alcohols with hindered hydroxyl groups may be difficult. Often the SN2 reaction is disfavored, and other methods of deoxygenation are needed. Various polyhydroxy compounds, such as carbohydrates and other carbohydratecontaining natural products, can be found in this group.
