An efficient and selective palladium-catalysed oxidative dicarbonylation of alkynes to alkyl- or aryl-maleic esters

Abstract

Terminal alkyne dicarbonylation can be readily effected under mild conditions b y treating alkynes with carbon monoxide and alcohols or water at 25-80°C in the presence of Pdlp, KI and air, with unprecedented catalytic efficiency. Dicarbonylated products are mainly maleic esters or acids and their ring-chain tautomers. The latter are formed to a large extent at room temperature. Reaction pathways are discussed.Dicarbonylation of alkynes with carbon monoxide has been known for several years,' but even the most recent literature reports methods which are not completely satisfactory particularly from the standpoint of catalytic efficiency. However, alkyl-or aryl-maleic esters and acids are interesting products, which can be used as monomers for polymerization, so an efficient procedure to prepare these compounds is a useful target. We now report such a procedure, which affords high yields of alkyl-or aryl-maleic esters and acids under mild conditions. A preliminary account, limited to prop-2-ynyl alcohol, was published r e c e n t l ~. ~

Oscillatory carbonylation of phenylacetylene in the absence of externally supplied oxidant

“…Gabriele et al [19] have previously reported the oxidative carbonylation of a variety of alkynes using PdI 2 /KI and palladium iodidethiourea (tu) catalysts with a thiourea/palladium ratio of 3 or 3. 2-is likely to be at least partially dissociated in methanol solution [18,19]. The mechanism of phenylacetylene carbonylation, as reported by Gabriele [18], is given in Eqs.…”

“…2-is likely to be at least partially dissociated in methanol solution [18,19]. The mechanism of phenylacetylene carbonylation, as reported by Gabriele [18], is given in Eqs. 1-4 (Scheme 1).…”

“…PdI 2 shows limited solubility in alcohol solvents. However, the soluble PdI 4 2-anion is formed and stabilized in solution upon introduction of excess KI [18]. Gabriele et al [19] have previously reported the oxidative carbonylation of a variety of alkynes using PdI 2 /KI and palladium iodidethiourea (tu) catalysts with a thiourea/palladium ratio of 3 or 3.…”

The effect of using a methanol–water solvent mixture on pH oscillations in the palladium-catalyzed phenylacetylene oxidative carbonylation reaction

“…Water has been shown to affect the behavior of the catalytic system used in the PCPOC reaction and is therefore proposed to be involved in the processes in the reaction mechanism that produce the pH oscillations [9,10]. Water also reacts in a similar manner to methanol (Scheme 1) leading to the isomeric diacids [(2Z)-2-phenyl-2-butenedioic acid and (2E)-2-phenyl-2-butenedioic acid] and phenylmaleic anhydride [11].…”

Autonomous reorganization of the oscillatory phase in the PdI2 catalyzed phenylacetylene carbonylation reaction

“…Using a PdI 2 -KI catalyst with alkynes under mild conditions, high catalytic efficiencies have been achieved leading to a mixture of dicarbonylation products [2]. When phenylacetylene (PhAc) was used as the substrate in methanol (palladium-catalyzed phenylacetylene oxidative carbonylation, PCPOC), oscillations in pH, redox potential and gas uptake (CO and O 2 ) were discovered [3][4][5][6][7].…”