ditosylate

A ditosylate is a chemical compound containing two p-toluenesulfonate (tosylate) ester groups. In organic synthesis, tosylates are excellent leaving groups, so a ditosylate typically arises from a difunctional substrate such as a diol that has been converted to the corresponding di-tosylate ester. The general form is two OTs groups attached to two alcohol-derived centers.

Preparation commonly involves treating a diol with p-toluenesulfonyl chloride (TsCl) in the presence of a base such as pyridine or triethylamine. An excess of TsCl is often used to ensure ditosylation, and catalysts like DMAP may accelerate the reaction. The reaction proceeds with the removal of HCl as a byproduct, yielding a di-tosylate in good to excellent yield under appropriate dry, aprotic conditions.

Properties of ditosylates include their stability as solids or viscous liquids, depending on the substrate. They are generally more reactive as leaving groups than the original alcohols and are used to activate two functional groups for subsequent nucleophilic substitution, cross-coupling, or cyclization reactions. Because both tosylate groups are good leaving groups, ditosylates can enable sequential or bimolecular transformations that install new bonds at two sites in a controlled manner.

Applications span various areas of organic synthesis, including the preparation of ethers, carbons-heteroatom bonds, and complex natural product frameworks. They are also used as intermediates in polymer and carbohydrate chemistry for selective activation of diol motifs.

Safety notes: tosyl chloride and ditosylates are typically irritants and corrosive toSkin and eyes; handle in a well-ventilated area with appropriate protective equipment. Store away from moisture and incompatible reagents.