A Highly Efficient Procedure for Ruthenium Tetroxide Catalyzed Oxidative Cyclizations of 1,5‐Dienes

We report a highly efficient procedure for the oxidative cyclization of 1,5‐dienes, which generally allows for high yields and selectivities. A solid‐supported terminal oxidant and a finely tuned solvent mixture have both been identified as critical factors for this high efficiency. As little as 0.2 mol‐% ruthenium(III) chloride as a pre‐catalyst for the ruthenium tetroxide generated in situ is required to accomplish oxidative cyclization. This exceptionally low catalyst loading, high diastereoselectivity, mild reaction conditions, and a simple workup procedure are key features of this process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)