Hydroxycarbonylation of Enol Triflates and lodoalkenes

Hydroxycarbonylation of vinyl triflates/halides has received considerable attention. The formation of carboxylic acids from palladium-catalyzed carbonylation of vinyl triflates is presumed to occur through the intermediacy of an unstable mixed anhydride. Hydroxycarbonylation of vinyl triflates has been reported to occur at room temperature in DMF under a CO balloon in the presence of Pd(OAc)2(PPh3)2 and potassium acetate [55]. The crucial role of the acetate anion is supported when the starting triflate is recovered after it has been reacted under usual conditions omitting potassium acetate. Acrylic acids have been obtained by palladium-catalyzed 

2 Reactions of a,P-Unsaturated Acylpalladium Complexes with Nucleophiles 233 

Interestingly, the procedure of hydroxycarbonylation by using lithium formate and acetic anhydride as internal condensed sources of carbon monoxide can be carried out in the presence of a recoverable and reusable phosphine-free palladium-carbon aerogel catalyst [61]. To support high-speed chemistry and automated organic synthesis, an operationally simple and environmentally safe hydroxycarbonylation of vinyl triflates can 

Moreover, the stereoselective palladium-catalyzed hydroxycarbonylation of vinyl halides to a, P-unsaturated carboxylic acids has been accomplished in ionic liquids as an alternative clean reaction media [64]. 

---