Conventional methods for preparing sulfones proceed via Mitsunobu reaction of the corresponding alcohol followed by oxidation. However, the Mitsunobu reaction is an inherently non-atom economical process which produces stoichiometric amounts of hydrazine dicarboxylate and triphenylphosphine oxide by-products, of which the latter can sometimes be difficult to separate from the final product.
Dartmouth scientists have now demonstrated that catalytic Ga(OTf)3 and trifluoroacetic acid (TFA), as a stoichiometric additive, promotes the hydrothiolation of unactivated alkenes with various thiols. The desired products are obtained in high yield with excellent selectivity for Markovnikov products. Using this method, sulfones can be synthesized that are commonly utilized in the modified Julia olefination reaction, a process that has been implemented in numerous syntheses of natural products and pharmaceutical agents for the preparation of stereodefined alkenes.
These findings are claimed in a pending patent application. We are seeking an industrial partner to further refine and market this technology. (Ref: J590)
Last Updated: 7/24/12