Adenosine, 2,3-diacetyl

Brydon and Roberts- added hemolyzed blood to unhemolyzed plasma, analyzed the specimens for a variety of constituents and then compared the values with those in the unhemolyzed plasma (B28). The following procedures were considered unaffected by hemolysis (up to 1 g/100 ml hemoglobin) urea (diacetyl monoxime) carbon dioxide content (phe-nolphthalein complex) iron binding capacity cholesterol (ferric chloride) creatinine (alkaline picrate) uric acid (phosphotungstate reduction) alkaline phosphatase (4-nitrophenyl phosphate) 5 -nucleotidase (adenosine monophosphate-nickel) and tartrate-labile acid phosphatase (phenyl phosphate). In Table 2 are shown those assays where increases were observed. The hemolysis used in these studies was equivalent to that produced by the breakdown of about 15 X 10 erythrocytes. In the bromocresol green albumin method it has been reported that for every 100 mg of hemoglobin/100 ml serum, the apparent albumin concentration is increased by 100 mg/100 ml (D12). Hemolysis releases some amino acids, such as histidine, into the plasma (Alb). 

Diacetyl-5 -deoxy-5 -(fluoromcthylsulfanyl)adenosine Typical Procedure ... 

A solution of 2, 3 -0-diacetyl-5 -deoxy-.5 -(mctliylsulfanyl)adenosine (1 mmol) in anhyd CH2CI2 (1 mL) was injected under argon into a stirred solution of XeF, (1.3 mmol) in CHjClj (4mL) at —60"C. The mixture was stirred at — 60 C for 6 h after which HMDS (1., 3 mmol) in CHjClj (I mL) was added to quench the HF formed. Volatile material w as removed under reduced pressure to leave a residue. The residue was purified by (lash chromatography (silica gel, EtOAc/hexane 4 1) to give the title compound yield 95 %. 

Free radical alkylation procedures have proved a useful route to alkylpurines which are not readily available by other methods. Thus 6-substituted purines including adenine and hypoxanthine may be converted into 8-methyl derivatives with t-butyl hydroperoxide in the presence of iron(II) ions and acid (74T2677), although small amounts of 2-methyl and 2,8-dimethyl derivatives were formed simultaneously. Adenosine and guanosine similarly furnished the corresponding 8-methyl derivatives with diacetyl peroxide (as a source of methyl radicals) and iron(II) ions (76T337). 

The ditrityl-adenosine was acetylated to give diacetyl-ditrityl-adeno-sine which, on hydrolysis by means of boiling 80% acetic acid, yielded the same diacetyl-adenosine (having o free amino group) as was obtained by hydrolysis of iV -acetyl-2,3-diacetyl-5-trityl-adenosine under the same conditions. It follows that the diacetate is 2,3-diacetyl-adenosine and that ditrityl-adenosine is 9 -(5-trityl-ribofuranosyl)-6 -N-trityl-adenine. 

These formulations were confirmed by treatment of the diacetyl-adenosine with p-toluenesulfonyl chloride, giving a ditosyl-diacetyl-adenosine, only one tosyloxy group of which was substituted by iodine on treatment with sodium iodide. Hence the ribose residue of adenosine has the furanose ring structure. 

Jachimowicz claimed to have synthesized 5-phosphoadenosine (in poor yield) by direct phosphorylation of adenosine with phosphorus oxychloride in pyridine, but Bredereck showed that a mixture of phosphoric esters of adenosine actually results, as might have been anticipated. Levene and Tipson succeeded in synthesizing 5-phospho-adenosine (in poor yield) by phosphorylation of 2,3-diacetyl-adenosine to give AT-phos-pho 5-phospho-2,3-diacetyl-adenosine, followed by deacetylation by alkali, and removal by acid-hydrolysis of the labile phospho group attached to nitrogen. (This synthesis was confirmed by Bredereck, et al. ) In a similar manner they phosphorylated 2,3-isopropylidene-adenosine to iV,5-di-phospho-2,3-isopropylidene-adenosine from which the acid-labile iV-phospho and isopropylidene groups were hydrolyzed, giving 5-phospho-adenosine. 

These difficulties were overcome in various ways, two of which were (1) isopropylidene tosyladenosine is condensed with vitamin B12 the acetone is removed from this compound by mild acid hydrolysis, and (2) the 5 -trityl adenosine is first synthesized and then converted to the 2, 3 -diacetyl trityl derivative, which is detritylated by dilute acid. The 2, 3 -diacetyl coenzyme is then prepared by tosylation and condensation. The compound is then deacetylated to give coenzyme Bi2 in good yields. 

The treatment of nucleosides with N,0-diacetyl-hydroxylamines in water or acetone causes alkylation of the bases, whereas in phosphate buffer at the same pH adenosine and guanosine are acetylated on the ribose units. 

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