Diols, acid catalyzed oxidative cleavage

Fig. 21. Ruthenium-catalyzed Oxidative cleavage of 9,10-dihy-droxystearic acid methyl ester by H2O2 in a two-phase system. Conditions RuCl3 DDAB diol H302 = 1 20 500 4000 (molar) 2 h at 80°C in 1,2-dicholethane. DDAB, didodecyidimethyl ammonium bromide.

Oxidative cleavage of alkenes to carboxylic acids.1 Alkenes are oxidized to carboxylic acids by H202 (35%) catalyzed by H2W04 in a weakly acidic medium (pH 4-5) maintained by addition of KOH. The oxidation probably involves initial oxidation to a 1,2-diol followed by dehydrogenation to an a-ketol, which is then cleaved to a mono- or dicarboxylic acid. 

Y. Ishii, K. Yamawaki, T. Ura, H. Yamada, T. Yoshida, M. Ogawa, Hydrogen peroxide oxidation catalyzed by heteropoly acids combined with cetylpyridinium chloride. Epoxidation of olefins and allylic alcohols, ketonization of alcohols and diols, and oxidative cleavage of 1,2-Diols and olefins,/. Org. Chem. 53 (1988) 3587. 

Ishii, Y, Yamawaki, K., Ura, T., et al (1988). Hydrogen Peroxide Oxidation Catalyzed by Heteropoly Acids Combined with Cetylpyridinium Chloride. Epoxidation of Olefins and Allylic Alcohols, Ketonization of Alcohols and Diols, and Oxidative Cleavage of 1,2-Diols and Olefins, J. Org. Chem., 53, pp. 3587-3593. 

Ishii, Y., Yamawaki, K., Ura, T., et al. (1988). Hydrogen Peroxide Oxidation Catalyzed by Heteropoly Acids Combined with Cetylpyridinium Chloride. Epoxidation of Olefins And Allylic Alcohols, Ketonization of Alcohols and Diols, and Oxidative Cleavage of 1,2-Diols and Olefins, J. Org. Chem., 53, pp. 3587-3593 Sato, K., Aoki, M., Ogawa, M., et al. (1997). A Halide-Free Method for Olefin Epoxidation with 30% Hydrogen Peroxide, Bull. Chem. Soc. Jpn., 70, pp. 905-915 Xi, Z. W., Zhou, N., Sun, Y., et al. (2001). Reaction-Controlled Phase-Transfer Catalysis for Propylene Epoxidation to Propylene Oxide, Science, 292, pp. 1139-1141 Neumann, R. 

The first enantioselective organocatalytic oxo-Michael reaction to enones was reported by Falck [109]. Falck developed the intramolecular addition of boronic acids hemiesters to enones catalyzed by thiourea catalysts. Alkyl, aryl, and heteroaryl y-hydroxy enones react with phenylboronic acid to furnish the corresponding boronic hemiesters 118, which after oxidative cleavage of the resulting dioxaboro-lane renders the chiral 1,2 diols 119 in excellent yields and enantioselectivities (Scheme 33.34). 

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