Abstract
In Rh(I) (Wilkinson)-catalyzed cyclization of 6-octen-1-als, the formation of cis-cyclohexanols is in contrast to Lewis acid-catalyzed cyclization, which affords predominantly the trans-cyclohexanols. However, 6-octen-1-als with a cyclic acetal (1, 3-dioxane or 1, 3-dioxolane) at the C3-position were stereoselectively cyclized to only the trans-products.The aldehyde with a chiral protecting group ((4R, 6R)-dimethyl-1, 3-dioxane with the C2-axis) at the C3-position was diastereoselectively cyclized to the trans-cyclohexanol, and on a basis of the absolute stereochemistry of the cyclized product, the cyclization mechanism is tentatively proposed. The effect of 4R-methyl-1, 3-dioxane at the C3-position was also examined.
