A SIMPLE AND MILD METHOD FOR THE DIRECT METAL-CATALYZED CARBONYLATION OF ALLYL ALCOHOLS TO ACIDS

Treatment of allyl alcohol with carbon monoxide in 5 N sodium hydroxide and toluene, using cetyltrimethylammonium bromide (CTAB) as the phase transfer catalyst and nickel cyanide as the metal complex [10/1 ratio of substrate/nickel catalyst], for 20 h at 90°C and 1 atm, results in 90% conversion of the alcohol. Work-up gave analytically pure crotonic acid in 68% isolated yield (all yields reported are isolated yields). This result contrasts with the use of allyl chloride as reactant which affords a mixture of 2- and 3-butenoic acids. This is an attractive method for the preparation of crotonic acid from allyl alcohol. The results presented are the first examples of the nickel-catalyzed direct carbonylation of allyl alcohols to acids in modest to excellent yields. Furthermore, the process proceeds under exceptionally mild conditions, and is simple in both execution and work-up.