Palladium(II)‐Catalyzed Isomerization of (<i>Z</i>)‐1,4‐Diacetoxy‐2‐Butene: Solvent Effects

Abstract

Abstract The isomerization of ( Z )‐1,4‐diacetoxy‐2‐butene ( 1 ) catalyzed by PdCl 2 (MeCN) 2 was studied in THF and DMF. The reaction occurs more rapidly in THF than in DMF, but in both solvents it did not proceed to complete consumption of the substrate and led to a mixture of 1 , ( E )‐1,4‐diacetoxy‐2‐butene ( 2 ), and 1,2‐diacetoxy‐3‐butene ( 3 ). The formation of 2 is more favored in DMF than in THF. The reactivity of 1 and the solvent effect differ strongly from those previously obtained with Pd(PPh 3 ) 4 as the catalyst. Interpretations are provided for the crucial role of the nature of both solvent and intermediates on the course of the isomerizations.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)