Triphenyl phosphite, ozone adducts

The reaction of singlet oxygen with conjugated double bonds usually is a 1,4-cycloaddition leading to formation of derivatives of the 1,2-diox -ene ring system. This can be achieved either by photooxidation or by reaction in the presence of triphenyl phosphite-ozone adduct (Section Vin.D.2), shown in equations 85 and 86 . ... 

The rather surprising observation has been made that gemacrene gives totally different products when it reacts with singlet oxygen, generated in a photosensitization reaction, than when it reacts with the triphenyl-phosphite-ozone adduct. There does not seem to be a clear-cut rationalization of this odd behaviour,... 

Anthryl ethers afford protection to alcohol functions treatment of the derivative with singlet oxygen, generated via the triphenyl phosphite-ozone adduct, followed by mild catalytic reduction, effects regeneration of the free alcohol (Scheme 136). 

Germacrene (318) reacts with the triphenyl phosphite-ozone adduct at —45°C at the 4,5-bond to give (319) after reduction, but with singlet oxygen initial attack occurs at the 7,13-bond, and further reaction gives the exocyclic... 

Decomposition of adducts such as triphenyl phosphite—ozone provides a convenient method for accomplishing chemical oxidations involving singlet oxygen and making it a useful oxygenating agent for synthetic and mechanistic appHcations. 

The trimethylsilylated ylides (1), easily generated from trimethyl chlorosilane and ylides, react with aldehydes 2 to form vi-nylsilanes 3 (2,3). The vinylphosphonium silanolates 4 are also formed. Compounds 3 are versatile reagents for further reactions (4). The ylide J (with R1 =H) reacts with aldehydes 2 to give the dienes j). The oxidation of with the adduct 6, from triphenyl-phosphite and ozone, gives access to a generaT synthesis of acyl-silanes (trimethylsilylketones) (2). The silylated ylides react to form phosphonium salts 7 with halogen compounds. The salts 7.can be desilylated by fluorine ions. The disubstituted ylides JO Tormed can be converted in statu nascendi with aldehydes V[ into the tris-substituted olefin J2 (2,3). In the case of R3-I, vinyl... 

Singlet oxygen2 (see also Triphenyl phosphite ozonide, this volume). Dilute methylene chloride solutions of this reagent (1) react quantitatively at—78° with one equivalent of ozone to give the 1 1 adduct (2).s The adduct decomposes at room temperature to the phosphate (3) with evolution of singlet oxygen as shown... 

Another highly interesting reaction, in which singlet oxygen is formed, was described by Murray and Kaplan [440—442]. An adduct of triphenyl-phosphite and ozone is prepared at —70°C. It decomposes at a temperature as low as —35°C with the liberation of singlet oxygen namely... 

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