TETRAHEDRON LETTERS Tetrahedron Letters 39 (1998) 7463-7466 Pergamon Ultrasound Accelerated Permanganate Oxidation: An Improved Procedure for the Synthesis of 1,2-Cis diols from Olefins Rajender S. Varma* and Kannan P. Naicker Department of Chemistry and Texas Regional Institute for Environmental Studies (TRIES), Sam Houston State University, Huntsville, Texas 77341-2117, U. S. A. Fax: (409)-294-1585; E-mail: CHM_RSV@SHSU.EDU Received 2 July 1998; revised 24 July 1998; accepted 29 July 1998 Abstract: A simple and expeditious method for the preparation of 1,2-cis diols is described from olefins using an inexpensive oxidant potassium permanganate, KMnO4, via sonochemical activation in aqueous media. © 1998Elsevier Science Ltd. All rights reserved. A large number of permanganate reagents have been developed for the oxidation of organic molecules under heterogeneous conditions. 1 Potassium permanganate supported on silica gel 2 or molecular sieves 3 has been used to oxidize alcohols to carbonyl compounds and for the cleavage 4a or oxidation 4b of carbon-carbon double bonds, permanganate supported on copper sulfate pentahydrate has been used for the oxidation of alcohols to the corresponding carbonyl compounds, 5 diols to lactones, 6 and sulfides to sulfones. 7 Zinc permanganate supported on silica gel is utilized for the conversion of acetylenes to c~-diketones and cyclic olefins to ketols. 8 The dihydroxylation of olefins is generally accomplished by osmium tetraoxide, OsO4, 9 and alkaline potassium permanganate, KMnO4, from the less-hindered side of the double bond. 1° The main drawback of this reaction is that OsO4 is expensive and highly toxic. Consequently, its use has been limited to small-scale preparations of scarce materials. Similar results are obtainable more economically by utilizing H202,11 t-butylhydroperoxide in alkaline media 12 0 r N-methylmorpholine-N-oxide 13 with judicious use of co-oxidant, OsO4 in smaller amounts. Potassium permanganate, on the other hand, is a strong oxidizing agent that can readily oxidize glycols 14 especially under acid and neutral conditions thus limiting its scope for the generation of glycols. Alkaline permanganate, however, can lead to glycol formation but the yields are seldom above 50%, although some improvement is feasible by employing phase transfer catalysis, 15 or extensive stirring in dilute solution. 16 We decided to explore the use of ultrasound irradiation in this oxidation protocol with KMnO4 which has been successfully applied earlier to a number of heterogeneous reactions 17 including the Baeyer's test for identifying the alkenes and alkynes. 18 Herein, we report a facile oxidative conversion of olefins to 1,2-cis diols in aqueous media 0040-4039•98•5 - see front matter © 1998 Elsevier Science Ltd. All rights reserved. PH: S0040-4039(98)01671-2