Cross-metathesis and ring-closing metathesis of olefinic monosaccharides

Cross-metathesis (CM) of a variety of carbohydrate-based C-6 and olefins with related C-1 and C-6 carbohydrate-based olefins proved to be unselective. CM was selective when an unhindered straight chain olefin was coupled with a carbohydrate-based C-6 olefin. When related short chain alkenols were tethered, via a Me2Si linker, to a suitably protected carbohydrate-based C-6 olefin, good yields of ring-closed products were obtained with the second-generation Grubbs catalyst 3. A few examples where two carbohydrate-based olefinic alcohols were tethered via a Me2Si linker and subjected to ring-closing metathesis (RCM) have also been examined.