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A novel three-component reaction of alkadienol, CO2, and aryl or vinylic halide gives a vinyl group-substituted cyclic carbonate in one pot in the presence of a catalytic amount of a palladium complex. 2,3-Alkadienol affords five-membered ring carbonate in good yield, while 3,4-alkadienol effects the six-membered one successfully. 2,4-Alkadienol also takes part in this reaction to provide five-membered ring carbonate. A reaction pathway involving a π-allylic palladium species as an intermediate has been presumed.

A cationic palladium complex, [Pd(PPh 3 ) 2 (MeCN) 2 ](BF 4 ) 2 , catalyzed the carbonylation of 2,3-dien-1-ols under mild conditions. The dienols bearing two or more alkyl substituents on the diene part afforded 1,3-diene-2-carboxylic acids successfully in tetrahydrofuran (THF), while those possessing one or no alkyl substituent gave polymers of the products exclusively. The former afforded the corresponding methyl esters in good yields when the reactions were carried out in methanol, while the latter afforded mainly the Diels-Alder reaction products of the resulting esters. An alkylidene group-substituted p-allylpalladium species has been presumed to be an intermediate.

A cationic palladium complex, [Pd(PPh3)2(MeCN)2](BF4)2, catalyzed the carbonylation of 2,3‐dien‐1‐ols under mild conditions. The dienols bearing two or more alkyl substituents on the diene part afforded 1,3‐diene‐2‐carboxylic acids successfully in tetrahydrofuran (THF), while those possessing one or no alkyl substituent gave polymers of the products exclusively. The former afforded the corresponding methyl esters in good yields when the reactions were carried out in methanol, while the latter afforded mainly the Diels–Alder reaction products of the resulting esters. An alkylidene group‐substituted π‐allylpalladium species has been presumed to be an intermediate. Copyright © 2000 John Wiley & Sons, Ltd.

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carboxylic acidscarboxylic acids (acyclic compounds) P 0250 -077Cationic Palladium Complex-Catalyzed Carbonylation of 2,3-Dien-1-ols to 1,3-Diene-2-carboxylic Acids and Esters under Mild Conditions.-A novel convenient access to the title dienecarboxylic acids (III) and (VIII)/(IX) as well as to their esters (V) and (X)/(XI), resp., is presented. It involves the Pd 2+ -catalyzed carbonylation of allenic alcohols (I) and (VII), resp., under mild conditions. The reaction proceeds in moderate to good yields for allenic alcohols bearing at least two substituents. The carbonylation of mono-or unsubstituted analogues [cf. (Id)] in THF proceeds with polymerization, while in methanol higher amounts of the cyclodimerization adduct [cf. (VI)] of the initially formed esters are obtained. -(UEMURA, K.; INOUE, Y.; Appl.