Inorganic pathway

Three main routes have been discovered in animals able to produce taurine (TAU), called the cysteine sulfinic acid (CSA) pathway, the cysteamine pathway and the inorganic pathway. 

The inorganic pathway,the enzymes of which have recently been isolated by Martin et al.(2),should be considered scarcely efficient in taurine production if it can be calculated that only one molecule of labeled taurine over a total of 40,000 has been found after administration of 20 pCi of labeled sulfate(3).In this route sulfate is firstly activated to adenosylphosphosulfate(APS), then to phosphoadenosylphosphosulfate(PAPS)which is transferred to aaminoacrylate(aAA)derived from serine. 

The pathway of plutonium dissolved in natural water, from a source such as a nuclear facility, to man, may be quite complicated. During the transport, the plutonium atoms encounter dissolved and particulate inorganic and organic matter, as well as minerals in rocks, sediment and soil, and living organisms which may metabolize the plutonium. Figure 1 depicts some of the more essential routes for plutonium between the point of emission and the plutonium consuming man. The overall effect of these pathways is that plutonium is slowly eliminated from the water, so that only a minor fraction of it reaches man. An example of this is that of the 4.2 tonnes of plutonium deposited on the earth after... 

The transfer of P from the continents to the ocean is separated into two distinct pathways. The flux of reactive P (F25) is estimated via measurements of dissolved organic and inorganic P in rivers. A small correction (33% after Kaul and Froelich, 1984) is added to the measured values to account for P released from particles within the estuaries. This P is transported directly to the surface ocean and is... 

The above transformations show a few of the many inorganic esters that can be prepared by attack of an inorganic acid or, better, its acid halide or anhydride, on an alcohol. Although for convenience all these similar reactions are grouped together, these are not all nucleophilic substitutions at R. The other possible pathway is nucleophilic substitution at the inorganic central atom ... 

Although the pathway has not been established, relatively high yields of trimethyltin from inorganic tin have been observed in yeast concomitant with the degradation of butyltin compounds (Errecalde et al. 1995). Exceptionally, methionine transferase may carry out the methylation of Hg in Neurospora crassa (Landner 1971) and thiopurine methyltransferase the methylation of inorganic Se in Escherichia coli (Ranjard et al. 2003). 

With a common intermediate from the Medicinal Chemistry synthesis now in hand in enantiomerically upgraded form, optimization of the conversion to the amine was addressed, with particular emphasis on safety evaluation of the azide displacement step (Scheme 9.7). Hence, alcohol 6 was reacted with methanesul-fonyl chloride in the presence of triethylamine to afford a 95% yield of the desired mesylate as an oil. Displacement of the mesylate using sodium azide in DMF afforded azide 7 in around 85% assay yield. However, a major by-product of the reaction was found to be alkene 17, formed from an elimination pathway with concomitant formation of the hazardous hydrazoic acid. To evaluate this potential safety hazard for process scale-up, online FTIR was used to monitor the presence of hydrazoic acid in the head-space, confirming that this was indeed formed during the reaction [7]. It was also observed that the amount of hydrazoic acid in the headspace could be completely suppressed by the addition of an organic base such as diisopropylethylamine to the reaction, with the use of inorganic bases such as... 

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