Preparation of trialkyl-substituted olefins by ruthenium catalyzed cross-metathesis

A summary of the application of ruthenium catalyzed olefin cross-metathesis towards the synthesis of selected natural compounds is given. Recent examples for the preparation of intermediates on the way to tocopherols (vitamin E) are discussed. This group of biologically most important fat-soluble antioxidants is synthetically available by various routes, for which key-building blocks containing trialkyl-substituted olefinic double bonds can now be prepared efficiently (isolated yields up to 83%). The results presented may be of interest for the area of syntheses of isoprenoid natural products in general.