Ruthenium‐Catalysed Selective Transetherification of Substituted Vinyl Ethers To Form Acetals and Aldehydes

The water‐soluble ruthenium allenylidene complex [{RuCl(μ‐Cl)(C=C=CPh2)(TPPMS)2}2]Na4 catalyses the selective transformation of substituted linear and cyclic vinyl ethers with MeOH, under mild non acidic conditions, to give acetals, while aldehydes and ketones are obtained in a CHCl3/H2O mixture, which allows for easy recycling of the catalyst. NMR studies showed that the reaction follows a transetherification mechanism rather than simple acid‐catalysed hydrolysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)