Electrochemical ozonolysis

Bieber reported that the reaction of bromoacetates is greatly enhanced by catalytic amounts of benzoyl peroxide or peracids and gives satisfactory yields with aromatic aldehydes. A radical chain mechanism, initiated by electron abstraction from the organometallic Reformatsky reagent, is proposed (Scheme 8.27).233 However, an alternative process of reacting aldehydes with 2,3-dichloro-l-propene and indium in water followed by ozonolysis provided the Reformatsky product in practical yields.234 An electrochemical Reformatsky reaction in an aqueous medium and in the absence of metal mediator has also been reported.235... 

Fission of carbon-carbon double bonds with the combined use of an osmium catalyst and periodate as a comsumable reagent is an alternative to ozonolysis. In diis process a catalytic amount of osmium is oxidised to osmium(viii) by preiodate and converts the alkene to a glycol which is then cleaved by the periodate. In the electrochemical modification of this process, which uses a divided cell and aque-... 

The alkoxyhydroperoxides, which are formed in the ozonolysis of olefins in alcohols, are electrochemically reduced to dialdehydes in very good yields 541 542> ... 

Thiazoline-azetidinone 36 is a versatile intermediate for the synthesis of varieties of beta-lactam antibiotics 24>. The most straightforward route to 36 must be the removal of the feta-lactam A-substituents of thiazoline-azetidinone 35, which is readily obtained from penicillins by Copper s method 4>. This has usually been done by the two-step operation, involving ozonolysis and subsequent methanolysis 25). Direct transformation of 35 to 36 also has been achieved by oxidation with potassium permanganate or osminum tetraoxide, but yields are unsatisfactory (—37%)25). An efficient method for the removal of A-substituents of 35 is the electrochemical acetoxylation procedure which may lead to the compound 36 along with 37 (Scheme 2-12)3). For example, the... 

In analyzing the literature, it seemed to me that a shorter and more economical route for the conversion of II to XIV might be created if we could improve on the 25-year-old electrochemical reduction method for converting 3-acetoxymethylcephalosporins to 3-exomethylene-cephalosporins (e.g., XVI) and thence to 3-hydroxycephalosporins (XV) via ozonolysis. Shionogi s Dr. Mitsuru Yoshioka and others pointed out that many people, notably at Takeda and Eli Lilly, had published the results of their extensive efforts to achieve such an electrochemical transformation but without commercial success.29 A review of this literature quickly revealed that the major impediments to commercialization were as follows ... 

It was characterized by chemical analysis, ozonolysis to form formaldehyde, hydrogenation, bromination and by its infrared and 1H-NMR spectra. The diene has also been prepared by pyrolysis of l,4-bis-(acetoxymethyl)cyclohexane (13,14), from cyclohexanedione by the Wittig reaction (11,15) or by reaction with diazomethane (16), and by the electrochemical or metal reduction of 1,4-dihalo-bicyclo-[2,2,2-]octanes (17,18) or of l,l,2,2-tetrakis-(bromo-methyl)-cyclobutane (19). It is very stable if stored in ammonia rinsed, dry flasks. 

Ozonolysis and electrochemical oxidation yield shorter ethoxylates than the starting material, fatty acid, fatty alcohols, and esters of fatty acids and ethylene glycol (89). 

Values reported for levels of APE and its metabolites vary too much to allow a statement of typical concentration. OPE is found at levels less than 10% of those of NPE, usually much less (93). Microbial degradation of the OPE metabolite octylphenoxyacetic acid results in formation of 2,4,4-trimethyl-2-pentanol (94). Ozonolysis of APE selectively destroys the aromatic ring, while electrochemical oxidation yield shorter ethoxylates than the starting material (89). A review of environmental analysis of APE appeared in 1997 (95). 

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