Homogeneous [RuIII(Me3tacn)Cl3]-Catalyzed Alkene cis-Dihydroxylation with Aqueous Hydrogen Peroxide

• Published in: Chemistry, an Asian journal an Asian journal, 2008-01, Vol.3 (1), p.70-77
• Main Authors: Yip, Wing-Ping, Ho, Chi-Ming, Zhu, Nianyong, Lau, Tai-Chu, Che, Chi-Ming
• Format: Article
• Language: English
• Subjects: alkenes; Alkenes - chemistry; Catalysis; dihydroxylation; Hydrogen Peroxide - chemistry; Hydroxylation; oxidation; Oxidation-Reduction; ruthenium; Ruthenium Compounds - chemistry; Water - chemistry
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200700237

A simple and green method that uses [Ru(Me3tacn)Cl3] (1; Me3tacn=N,N′,N′′‐trimethyl‐1,4,7‐triazacyclononane) as catalyst, aqueous H2O2 as the terminal oxidant, and Al2O3 and NaCl as additives is effective in the cis‐dihydroxylation of alkenes in aqueous tert‐butanol. Unfunctionalized alkenes, including cycloalkenes, aliphatic alkenes, and styrenes (14 examples) were selectively oxidized to their corresponding cis‐diols in good to excellent yield (70–96 %) based on substrate conversions of up to 100 %. The preparation of cis‐1,2‐cycloheptanediol (119 g, 91 % yield) and cis‐1,2‐cyclooctanediol (128 g, 92 % yield) from cycloheptene and cyclooctene, respectively, on the 1‐mol scale can be achieved by scaling up the reaction without modification. Results from Hammett correlation studies on the competitive oxidation of para‐substituted styrenes (ρ=−0.97, R=0.988) and the detection of the cycloadduct [(Me3tacn)ClRuHO2(C8H14)]+ by ESI‐MS for the 1‐catalyzed oxidation of cyclooctene to cis‐1,2‐cyclooctanediol are similar to those of the stoichiometric oxidation of alkenes by cis‐[(Me3tacn)(CF3CO2)RuVIO2]+ through [3+2] cycloaddition (W.‐P. Yip, W.‐Y. Yu, N. Zhu, C.‐M. Che, J. Am. Chem. Soc. 2005, 127, 14239). Clean and green: An environmentally friendly and practical method was developed for alkene cis‐dihydroxylation with [Ru(Me3tacn)Cl3] as catalyst and H2O2 as the terminal oxidant. Good to excellent yields of cis‐diol products were obtained from cyclic, aliphatic, and aromatic alkenes. Me3tacn=N,N′,N′′‐trimethyl‐1,4,7‐triazacyclononane.