Relations reductive

Dye release may relate either directly or inversely to the image-related reduction of silver halide. Release of the dye or dye precursor may be accomphshed or initiated by the oxidized developing agent or the unoxidized developing agent or by alkali or silver salts. 

In this section primarily reductions of aldehydes, ketones, and esters with sodium, lithium, and potassium in the presence of TCS 14 are discussed closely related reductions with metals such as Zn, Mg, Mn, Sm, Ti, etc., in the presence of TCS 14 are described in Section 13.2. Treatment of ethyl isobutyrate with sodium in the presence of TCS 14 in toluene affords the O-silylated Riihlmann-acyloin-condensation product 1915, which can be readily desilylated to the free acyloin 1916 [119]. Further reactions of methyl or ethyl 1,2- or 1,4-dicarboxylates are discussed elsewhere [120-122]. The same reaction with trimethylsilyl isobutyrate affords the C,0-silylated alcohol 1917, in 72% yield, which is desilylated to 1918 [123] (Scheme 12.34). Likewise, reduction of the diesters 1919 affords the cyclized O-silylated acyloin products 1920 in high yields, which give on saponification the acyloins 1921 [119]. Whereas electroreduction on a Mg-electrode in the presence of MesSiCl 14 converts esters such as ethyl cyclohexane-carboxylate via 1922 and subsequent saponification into acyloins such as 1923 [124], electroreduction of esters such as ethyl cyclohexylcarboxylate using a Mg-electrode without Me3SiCl 14 yields 1,2-ketones such as 1924 [125] (Scheme 12.34). 

Because of the potential of gaining structural information for reductively [ CJmethylated glycophorins and by pH-titration studies, the pH-titration behavior of reductively, di[ C]methylated glycophorins A and A, and 28 related, reductively di[ C]methylated glycoproteins, glycopep-tides, and peptides in HjO and D2O were investigated. These results are presented in Table II, and Figs. 10 and II. 

This article mostly focuses on the catalytic pinacol coupling and related reductive transformations via one-electron transfer. On the other hand, the corresponding methods for catalytic oxidative transformations via one-electron oxidation have been scarcely investigated and remain to be developed. Both methods are complementary and useful for generating radical intermediates. 

The synthetic method leading to Nb-alkylidenes and Nb-alkylidynes was particularly successful, due to a quite remarkable difference in the reaction rate of 29 with ketones or aldehydes, vs the subsequent reaction of the alkylidene with ketones and aldehydes (see Scheme 37). The former reaction takes a few minutes at -40°C, while the latter one occurs in hours at room temperature.88 The reaction between 178 and benzaldehyde led to triphenylethylene and the niobyl derivative 184. Due to the difference in reaction rates between a and b in Scheme 37, it was found that the sequential addition of two different ketones or aldehydes to a THF solution of 29 produced a nonsymmetric olefin in a stepwise McMurry-type reaction.84 This is exemplified in the coupling shown in reaction c (Scheme 37). The proposed reaction pathway does not involve the intermediacy of a pinacolato ligand and therefore differs from the mechanism of the McMurry reaction and related reductive couplings at activated metal sites.89... 

Dose-related reduction in size of seminiferous tubules and in percentage of damaged tubules. High-dose group experienced 24-58% reduction in spermatogenesis (and high death rate) low-dose group 11-21% reduction and controls 0.5-6.1% reduction (Balash etal. 1987)... 

Doses of 5 ng/fish and higher led to dose-related reduction of egg numbers and to lethal developmental abnormalities in their offspring ovaries of parents were abnormal histologically... 

Age-related reductions in bone marrow reserve can render the elderly patient more susceptible to anemia that is caused by multiple minor and often unrecognized diseases (e.g., nutritional deficiencies) that negatively affect erythropoiesis. 

Pregnant mice exposed to 40, 200, or 1000 ppm 1,3 butadiene 6 hours/day on gestational days 6-15 had maternal toxicity at the two highest dose groups significant exposure-related reductions in the mean body weights of male fetuses occurred at 40 ppm and higher. There was no evidence of selective developmental toxicity in rats similarly exposed, and no increased incidence of malformations was observed in either study. " ... 

Clearly, an expert interpretation of teratology data cannot be reduced to a mathematical algorithm or flowchart. The teratologist uses his knowledge of the test system to make sense of the fluctuations observed and also to rule out any implausible effects. For instance, a difference in pre-implantation loss in a routine teratology study with the start of dosing on gestation day (CD) 6 is unlikely to be due to the test item. Likewise, a treatment-related reduction in resorption incidence is implausible since zero loss is within the limits of normality. 

There are hundreds of published studies on the effects of benzodiazepine anxiolytics and hypnotics on ptr/ermam-e parameters m healthy subjects, and it is generally recognized that these drugs cause a dose-related reduction m most... 

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