Lead tetraacetate, oxidation compound

Cycloalkoxy radical intermediates are readily generated from a parent alcohol by various methods (e.g., nitrite ester photolysis, hypohalite thermolysis, lead tetraacetate oxidation) (83MI1). Once formed, reactive cycloalkoxy radicals undergo /3-scission to produce a carbonyl compound and a new carbon-centered radical. 

Lead tetraacetate, oxidation of a hydrazone to a diazo compound, 50, 7 Lithio ethyl acetate, 53, 67 Lithium, reductions in amine solvents, 50, 89 Lithium aluminum hydride, reduction of exo-3,4-dichloro-bicyclo-[3.2.l]oct-2-ene to 3-chlorobicyclo[3.2.l]oct-2-ene, 51, 61... 

The diacetamide compounds were regularly obtained in all degradations employing ammonia with or without silver oxide until Hockett and Chandler applied the method to hexaacetyl-D-gluco-D-flruZo-heptono-nitrile (XLIX) and obtained a monoacetamide derivative that was identified as iV-acetyl-D-glucofuranosylamine (L). The furanose structure of L was established by lead tetraacetate oxidation. They... 

The hydrolysis of these model precursors was studied at 37 , with catalysis by hog liver esterase. The major product, isolated in 60-70% yield from the hydrolysis of a-acetoxyNPy, was 2-hyd oxy-tetrahydrofuran. This compound was identified by comparison to a reference sample,prepared by lead tetraacetate oxidation of 1,2,5-pentanetriol (53). Additional evidence was obtained by lithium aluminum hydride reduction of the product to 1,4-butanediol. Minor amounts of butenals were also identified as products of the hydrolysis of a-acetoxy IPy. 

The structures of the di-O-isopropylidene acetals of deatfro-inositol and Zero-inositol were determined by lead tetraacetate oxidation, and the results of these degradations confirmed the configurations previously assigned to the two active inositols.1 The dextro compound gave61 the di-O-isopropyl-idene acetal of D-monno-hexodialdose (LVII), which was reduced by sodium... 

More complex ellagitannins, such as the natural compounds tellimagrandin I (162) [117], sanguiin H-5 [18], pedunculagin [118], and coriariin A (166) (Scheme 41) [119, 120] have also been synthesized by the lead tetraacetate oxidative coupling procedure, with the same favorable stereoselective (S)-biaryl bond formation. 

One of four products resulting from the lead tetraacetate oxidation of the dihydrazone (274) in the presence of phenyl azide is tetramethylthieno[3,4-rf ][ 1,2,3 Jtriazole (276) the bis(diazo) compound (275) is the presumed intermediate (81JA2868). 

As an alternative to the lead tetraacetate oxidation, (diacetoxyiodo)benzene can be used to initiate a fragmentation reaction which leads to unsaturated medium-sized lactones [110]. The structures of the starting materials are similar to those of compounds VII/157, VII/160, and VII/163. The same stereochemical consequences are observed as mentioned above. 

Methoxyvincamine (vincine, XXXV R = OMe), whose ring A methoxyl is so placed because of its UV-spectrum and a color reaction specific for that position, had properties (Chart III) that paralleled those of vincamine (21). This conclusion was reached independently on the basis of mass spectral comparisons (18). The stereochemistry of both alkaloids is regarded as being the same (21). Tetradehydro compounds (XXXVII) were formed by lead tetraacetate oxidation, and XXXVII... 

In addition to the Dimroth rearrangement of [l,2,4]triazolo[3,4-c][l,2,4]triazines discussed in the last section, derivatives of (42) would probably be accessible by the general application of a special case which involved the reaction of l-acetonyl-5-chloro-l,2,4-triazole (356) with hydrazine to produce the dihydro compound (357). Lead tetraacetate oxidation of (357) formed (358) (77JOC1018). 

Another variant is oxidative cyclization of 3-amino-2-carbalkoxyquinones with lead tetraacetate (85JHC697). Compounds of the 196 system can be regarded as intramolecular stabilized nitrenes. They react readily with dimethyl sufoxide by ring opening of the heterocyclic part (85JHC701), but derivatives of 198 were also obtained as by-products (85JHC705). 

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