Purines with alcohols

Salomon J, Elad D (1973) Photochemical reactions of nucleic acid constituents. Peroxide-initiated reactions of purines with alcohols. J Org Chem 38 3420-3421 Salomon J, Elad D (1974) Ultraviolet and y-ray-induced reactions of nucleic acid constituents. Reactions of purines with amines. Photochem Photobiol 19 21-27 Samuni A, Neta P (1973) Hydroxyl radical reaction with phosphate esters and the mechanism of phosphate cleavage. J Phys Chem 77 2425-2429... 

A few effective methods have been reported for the direct formation of 8-alkyl- or 8-(hydroxy-alkyl)purines from the parent purine. These reactions are mainly photoreactions of purines with alcohols, ethers, amines, and amino acids. For a review see ref 45. 

Most of the photoalkylations of purines with alcohols lead to the substitution of H8 by a hydroxyalkyl group. The reactions are mainly initiated either directly by UV light (/ > 260 nm) or via photosensiti/ation with acetone or peroxides and light (2 > 290 nm). A typical example is the photoalkylation of 6-ethoxypurine (1) with propan-2-ol. ... 

Radiation-induced reactions of purines with alcohols... 

Leonov D, Salomon J, Sasson S, Elad D (1973) Ultraviolet- and y-ray-induced reactions of nucleic acid constituents with alcohols. On the selectivity of these reactions for purines. Photochem Photobiol 17 465-468... 

Steenken S, Jovanovic SV, Candeias LP, Reynisson J (2001) Is frank" DNA-stand breakage via the guanine radical thermodynamically and sterically possible Chem Eur J 7 2829-2833 Steinmaus H, Rosenthal I, Elad D (1969) Photochemical and y-ray-induced reactions of purines and purine nucleosides with 2-propanol. J Am Chem Soc 91 4921-4923 Steinmaus H, Rosenthal I, Elad D (1971) Light- and y-ray-induced reactions of purines and purine nucleosides with alcohols. J Org Chem 36 3594-3598 Stelter L, von Sonntag C, Schulte-Frohlinde D (1974) Radiation chemistry of DNA-model compounds, V. Phosphate elimination from ribose-5-phosphate after OH radical attack at C-4. Int J Radiat Biol 25 515-519... 

A comparison of the structure of 1,6-dihydropurine with those of the 1 1 photoadducts of alcohols to purine reported by Linschitz Connoly 156> 157), which are formally identical, suggests that the latter should be equally susceptible to photo-dissociation to the parent purine and alcohol. The same probably applies to the photoadducts of alcohols to 6-methylpurine. 

Free radical reactions of purines with amines gave similar products to those produced in alcohol solution although deamination may also occur, probably at the post- rather than the pre-adduct stage. Whereas purine and n-propylamine afforded 6-n-propylpurine (71MI40907), adenine and caffeine produced both the 8-aminoalkyl and corresponding 9-alkyl derivatives (74MI40904). Also irradiation of 8-aminoalkylpurines in methanol furnished the 8-alkyl derivatives. Amino acids as an amine source are of special biochemical interest. They also tend to produce 8-alkylpurines by concomitant deamination and decarboxylation (69CC905). 

Corresponding reactions to those noted above with alcohols are found to occur with amines, the radical produced being derived by hydrogen abstraction from the carbon linked to the heteroatom. Radical generation can be effected with y-irradiation or UV light (> 250 nm or > 290 nm) using either liquid amines or aqueous solutions. The tendency to lose the heteroatom from the radical moiety is more pronounced than with the alcohol derivatives. The extreme case is found with 6-unsubstituted purines, in which no 6-aminoalkylpurine is obtained concomitant deamination occurs giving the 6-alkylpurine as product (Scheme 7). 

Reactions of 1,2-diaminoalkenes with alcohols, aldehydes, or carboxylic acids and derivatives at high temperatures in the presence of a dehydrogenating agent are common approaches to the synthesis of 2-substituted imidazoles <89KFZ1246>. In the absence of the dehydrogenating agent the products are imidazolines. The method is particularly applicable to the synthesis of purines from... 

These mutagenic studies showed that lucidin can be metabolised to a reactive compound which forms covalent adducts with DNA and possibly other macromolecules. It was reported that lucidin forms ethers and esters upon heating with alcohol or acids. This supports the reactive character of lucidin [57,97,153]. Kawasaki et al. (1994) proved that lucidin forms adducts with the nucleic acids adenine and guanine under physiological conditions [159]. These adducts were identified as condensed reactants at the benzylic position of lucidin with a nitrogen atom of a purine base. This... 

In Fig. 4 this is demonstrated under the conditions of the purine loading test. In the case of purine-rich food in combination with alcohol abuse a cumulative effect must even be expected. 

As an aromatic sulphonyl chloride, Dns-Cl reacts with primary and secondary amino groups even at slightly alkaline pH it reacts at higher pH with phenols, imidazoles, and even slowly with alcohols. Derivatives with barbiturates, purines and carbamates are also known. Thiol compounds form the corresponding disulphides [7, 17]. 

The degree of response to purine restriction was also related to the extent of usual alcohol consumption. Ten males whose usual alcohol consumption was minimal or, at most, less than 20 ml of ethanol daily were compared with another group whose usual ethanol consumption was consistently greater than 20 ml of ethanol daily. As shown in Table 3, there was a significantly greater fall in the serum urate concentration in the heavier alcohol consumers. Moreover, the serum urate concentrations were the same during the period of purine and alcohol restriction in the minimal alcohol drinkers as in the heavier alcohol drinkers. Thus, the fall in serum urate with purine and alcohol restriction was significantly... 

Polar functional groups such as alcohols or phenols 11 or trimethylsilanol 4 are transformed by monofunctional silylating reagents Me3SiX 12 into their hpophilic and often volatile trimethylsilyl ethers 13 whereas water is converted into persilyl-ated water (=Me3SiOSiMe3, hexamethyldisiloxane, HMDSO, 7, b.p. 100 °C). The persilylation of phenols and, in particular, catechol (or hydroquinone) systems (Scheme 2.1) protects them efficiently against air oxidation even at temperatures of up to 180 °C. (cf, e.g., the silylation-amination of purine nucleosides with dopamine hydrochloride in Section 4.2.4)... 

Last but not least HMDS 2 is, in the laboratory and in pilot plants, quite stable when stored in a normal closed vessel whereas trimethylchlorosilane (TCS) 14 should be stored in a hood, because it reacts with humidity to hexamethyldisilox-ane 7 and HCl. Because HMDS 2 is a very non-polar compound, the silylation of very polar compounds, e.g. purines or pteridines, with HMDS 2 wiU often proceed only on addition of a polar solvent such as pyridine which is, however, readily removed after silylation, with excess HMDS 2, on codistillation with abs. xylene. Interestingly, it was recently reported that addition of catalytic amounts of iodine dramatically accelerates the silylation of alcohols, in particular tertiary alcohols, with HMDS 2 in CH2CI2 at room temperature [63]. 

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