STEREOCHEMISTRY OF THE PERMANGANATE OXIDATION OF 1,5-DIENES

In 1965 Klein and Rojahn reported that oxidation of 1,5-dienes structurally related to geraniol and nerol[formula ommitted]with potassium permanganate under slightly alkaline conditions afforded 2,5-bis(hydroxymethyl) tetrahydrofurans 2 with relative stereochemistry as shown in eq l.1,2From a mechanistic viewpoint, these results [formula ommitted] are provocative, particularly in light of the recent proposals of Sharpless concerning the mechanism of oxidations of olefins by oxo transition metal species.3 They are especially intriguing from the standpoint of synthetic chemistry in suggesting that stereocontrolled synthesis of 2,5-bis(hydroxymethyl)tetrahydrofurans 2 with four chiral centers [formula ommitted] may be accomplished via stereoselective synthesis of the appropriate 1,5-diene precursor. To our knowledge, no report concerning permanganate oxidation of a 1,5-diene containing four unsymmetrically substituted olefinic carbons [formula ommitted] has appeared in the literature, and no quantitative analytical data regarding the extent of stereospecificity of the transformation for any 1,5-diene is available for mechanistic consideration. Therefore, as part of a study on the scope and mechanism of this reaction, particularly relating to the development of methodology for stereocontrolled total synthesis of tetrahydrofuran containing natural products (e.g.,monensin4), we describe here our work on the oxidation of the three isomeric 2,6-octadienes. © 1979, American Chemical Society. All rights reserved.