ジオールの新しい保護基、トリイソプロピルシリルアセトアルデヒドアセタール

抄録

The title acetal has been prepared from allyltriisopropylsilane in two steps in 60-75% yield. This acetal can react with 1,2- or 1,3-diols in the presence of acid catalyst to give the corresponding 1,3-dioxolane or 1,3-dioxane in excellent yields. The cyclic acetal is relatively stable under weak acidic conditions. For example, it survives in acetic acid at 80 °C or PPTS in organic solvents. This protecting group can be removed under mild conditions by the treatment of LiBF₄ in acetonitrile to give the starting diol efficiently. However, it is hardly deprotected with tetrabutylammonium fluoride. In addition, HF/pyridine can use for the deprotection of 1,3-dioxolane derivatives but not 1,3-dioxane derivatives. Selective protection/deprotection for 1,2- and 1,3-diols can be achieved by the use of triisopropylsilylacetal. Particularly, tolerance of acetal to acids is valuable for organic synthesis.

fig.1