Purine 2,6-dichloro-9-

Purine, 2,6-dibromo-9- -D-ribofuranosyl-synthesis, 5, 594 Purine, 6,8-di-t-butyl-amination, 5, 542 Purine, 2,6-dichloro-alkylation, 5, 530 reactions... 

Dichloro-9-[2-benzoyloxyethoxymethyl]purine was prepared as a key intermediate, which upon selective substitution of the 6-chloro group by ammonia followed by deamination and then displacement of the 2-chloro group gave 9-(2-hydroxyethoxymethyl)guanine. The use of the same synthetic procedure led to a variety of analogs. Of these ACV was found to... 

Preparation 313.—2 6-Dichlorouric Acid (2 Q-Dichloro-8-hydroxy-purine). 

Purine, 6-amino-2-benzyloxy-9-methyl-hydrogenolysis, 5, 558 Purine, 2-amino-6-chloro-reactions, 5, 562 Purine, 6-amino-2,8-dichloro-hydrogenolysis, 5, 563... 

In a separate report, the regioselectivity and reactivity problems in the substitution of pyrimidines were avoided using 4,6-dichloro-5-nitropyrimi-dine as starting material,17 a very electron-poor heterocycle, which is highly reactive in nucleophilic aromatic substitutions. It reacts readily with the free amino group of the (trialkoxybenzhydrylamine) Rink linker on solid phase. This heterocycle could serve as a scaffold by itself and could also be used as a building block (precursor) to make other heterocycles such as purines. 

Robins, M. J. Uznanski, B. Nucleic Acids Related Compounds. 33. Conversions of Adenosine and Guanosine to 2,6 Dichloro, 2-Amino-6-chloro, and Derived Purine Nucleosides. Can. J. Chem. 1981, 59, 2601-2607. 

However, treatment of 2,6-dichloro-9-(2,3,5-tri-0-acctyl-j5-D-ribofuranosyl)purine with anhydrous ammonia in anhydrous 1,2-dimethoxyethane results in selective displacement of the 6-chloro substituent without hydrolysis of the ester functions to give 8. ... 

Dry NHj gas (passed through a drying tube packed with CaH ) was bubbled slowly through a solution of 2,6-dichloro-9-(2,3,5-tri-0-acetyl-/ -D-ribofuranosyl)purine (1.0 g, 2.2 mmol, dried at 60 C in vacuo) in anhyd DME (20 mL, distilled directly from NaH into the dried reaction flask) at rt for 8 h. The solution was evaporated and the colorless residue was treated with CIICI3 (10 mL). This suspension was applied to a column of silica gel (50 g, 2 x 45 cm). CHClj/acetone with an increasing gradient of acetone was used for elution. The appropriately pooled fractions were evaporated and the resulting colorless solid foam was dissolved in CHCI, /i-PrOH. The product crystallized upon slow evaporation of the solution. It was filtered, washed with EtjO, and dried yield 857 mg (91%) mp 151-152°C. 

Dichloro-2-(methylsulfanyI)purine (3 g, 13 mmol) was covered with 1 M KSH (40 mL), and the mixture was refluxed for 4 h. The hot solution was then treated with charcoal and filtered, and the warm filtrate was acidified with glacial HOAc, The mixture was filtered after standing for 30 min, and the product was washed with water and dried at 110 C yield 2.7 g (91 %) yellow needles. 

Dichloro-9-(2,375-tri-0-acetyl- -D-ribofuranosyl)purine (8, X = Cl) Typical Procedure ... 

C5H4N4S 1,7-dihydro-6H-purine-6-thione 50-44-2 25.00 1 4634 2 4478 C5H6CI202 2,2-dichloro-l-methyl-cyclopropanecarboxylic 1447-14-9 22.50 1.3010 2... 

It is quite often most convenient to prepare a desired purine nucleoside by transformations at the purine moiety of another purine nucleoside. Perhaps the most useful and frequently employed transformation is the nucleophilic displacement of a chlorine atom or an alkylthio group attached to C-2, C-6, or C-8 of the purine nucleus. In his early work, Fischer established that the order of reactivity of the chlorine atoms attached to a purine is Cl-6 > Cl-2 Cl-8, so that, by choosing the proper sequence of reactions, a variety of products can be obtained. Thus, as already described, Fischer was able to prepare the n-glucosyl analogs of adenine and guanosine by the appropriate transformations of 2,8-dichloro-9- -D-glucopyranosyladenine. 

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