Palladium-catalyzed oxidative Heck reaction of non-activated alkenes directed by fluorinated alcohol.

A novel, Pd-catalyzed oxidative Heck reaction of non-activated alkenes synergistically directed by bifunctional groups has been developed firstly by using O2 as a green oxidant, yielding the oxidative Heck products with excellent yields in a regio- and stereoselective manner. This bifunctional synergistic activation mechanism was demonstrated by experimental analysis and detailed computational studies, wherein the hydroxyl group directs the migratory insertion of the alkenes and the trifluoromethyl group facilitates the subsequent ß-H elimination and reductive elimination. Moreover, a pesticidal active compound was synthesized using the bifunctional synergistically directed C-H arylation as the key step, which demonstrated its synthetic utility.

Selective Synthesis of Non-Aromatic Five-Membered Sulfur Heterocycles from Alkynes by using a Proton Acid/N-Chlorophthalimide System.

A multicomponent strategy to achieve two different regioselectivities from alkynes, isothiocyanates and H2 O with a proton acid/N-chlorophthalimide (NCPI) system is described to selectively obtain non-aromatic five-membered sulfur heterocycles (1,3-oxathiol-2-imines/thiazol-2(3H)-one derivatives) through multiple bond formations. The process features readily available starting materials, mild reaction conditions, broad substrate scope, good functional-group tolerance, high regio- and chemo- selectivities, gram-scale synthesis and late-stage modifications. Mechanistic studies support the proposal that the transformation process includes a combination of H2 O and isothiocyanate, free-radical formation, carbonation and intramolecular cyclization to give the products. Furthermore, the 1,3-oxathiol-2-imine derivatives possess unique fluorescence characteristics and can be used as Pd2+ sensors with a "turn-off" response, demonstrating potential applications in environmental and biological fields.