- The alkylation of 6-chloropurine with alcohols by Mitsunobu reaction
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A general procedure has been developed for the preparation of 9-alkylated adenines by the Mitsunobu reaction between 6-chloropurine and several alcohols, followed by the replacement of the chlorine with ammonia. A lesser amount of the 7-alkylpurines was also obtained, irrespective of the alcohol used.
- Toyota,Katagiri,Kaneko
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Read Online
- Antiviral properties and interaction of novel chalcone derivatives containing a purine and benzenesulfonamide moiety
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A new concise and facile method was explored to synthesize a series of novel chalcone derivatives containing a purine and benzenesulfonamide moiety and their antiviral properties were evaluated against TMV and CMV. Biological assays indicated that several
- Zhou, Dagui,Xie, Dandan,He, Fangcheng,Song, Baoan,Hu, Deyu
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Read Online
- Regioselective alkylation reaction of purines under microwave irradiation
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The alkylation of purines which is generally carried out after anion formation by treatment with a base and alkyl halide is complicated and in the best cases, mixtures of N-alkylated compounds are obtained. Purine derivatives can be acquired from alkylati
- Ginard, Jaume,Jahani, Daniel,Mur, Nuria,Pujol, Maria Dolors,Vi?as, Miquel,Vinuesa, Arturo
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- Synthesis of novel selenotetrazole purine derivatives and their potential chemotherapeutic activities
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The development of novel chemotherapeutic agents is indispensable to improve cancer treatment. One of the conventional approaches toward the synthesis of anticancer agents is the design of a compound whose structure is similar to purines found in DNA. In this study, a series of novel artificial purine nucleosides bearing selenotetrazole pharmacophore, 4a–4h, were synthesized. In order to get preliminary information about their cytotoxic activities, the interaction of compounds with DNA was investigated by UV titration and agarose gel electrophoresis and transcription inhibition studies were performed. The cytotoxic effects of the compounds against B16 melanoma, OV90 ovarian cancer, JM1 lymphoma cell lines, and PHA-induced peripheral blood lymphocytes were also investigated. In cell assay studies, the effects of the compounds on synthesis and mitosis stage of cell cycle were compared by flow cytometry. Although none of the compounds synthesized interacted with DNA and exhibited transcription inhibition, all of them significantly inhibited DNA synthesis phase and showed cytotoxic activity on cancer and proliferating cells. [Figure not available: see fulltext.]
- Dilek, Gulay,Tekin, Ishak Ozel,Coban, Burak,Disli, Ali,Gercek, Zuhal
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- A modular approach for the installation of functionalized phosphonates to heterocycles
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Phosphonic acids and esters are pervasive throughout the discovery sciences, from medicine and agriculture, to materials and asymmetric synthesis. The ability to install and construct molecular architecture containing phosphonic functionality has led to t
- Shultz, Zachary,Shan, Chuan,Wojtas, Lukasz,Lopchuk, Justin M.
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- C-H amination of purine derivatives via radical oxidative coupling
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An oxidative coupling reaction between purines and alkyl ethers/benzyl compounds was developed to synthesize a series of N9 alkylated purine derivatives using n-Bu4NI as a catalyst and t-BuOOH as an oxidant. This protocol uses commercially available, inexpensive catalysts and oxidants and has a wide range of substrates with a simple operation.
- Luo, Zheng,Jiang, Ziyang,Jiang, Wei,Lin, Dongen
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p. 3710 - 3718
(2018/04/14)
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- Purine-ring-containing benzene sulfonamide chalcone derivative and preparation and application methods thereof
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The invention discloses a purine-ring-containing benzene sulfonamide chalcone derivative and preparation and application methods thereof. The purine-ring-containing benzene sulfonamide chalcone derivative has a formula (I) shown as below, in which R1 is 4-oxymethyl, 4-tert-butyl, 4-methyl, 4-flouride, 4-bromide, 2-methyl, 2-fluoride, 2-chloride, 2-bromide and hydrogen atom and R2 is methyl, ethyland benzyl. The purine-ring-containing benzene sulfonamide chalcone derivative can inhibit tobacco mosaic virus, cucumber mosaic virus, potato Y virus and southern rice black-streaked dwarf virus.
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Paragraph 0030
(2019/01/05)
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- Structure-metabolism relationships in human-AOX: Chemical insights from a large database of aza-aromatic and amide compounds
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Aldehyde oxidase (AOX) is a metabolic enzyme catalyzing the oxidation of aldehyde and aza-aromatic compounds and the hydrolysis of amides, moieties frequently shared by the majority of drugs. Despite its key role in human metabolism, to date only fragmentary information about the chemical features responsible for AOX susceptibility are reported and only "very local" structure-metabolism relationships based on a small number of similar compounds have been developed. This study reports a more comprehensive coverage of the chemical space of structures with a high risk of AOX phase I metabolism in humans. More than 270 compounds were studied to identify the site of metabolism and themetabolite(s). Both electronic [supported by density functional theory (DFT) calculations] and exposure effects were considered when rationalizing the structure-metabolism relationship.
- Lepri, Susan,Ceccarelli, Martina,Milani, Nicolò,Tortorella, Sara,Cucco, Andrea,Valeri, Aurora,Goracci, Laura,Brink, Andreas,Cruciani, Gabriele
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p. E3178 - E3187
(2017/04/24)
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- The Convenient Synthesis of Unsaturated Nucleoside Analogues in Water under Microwave Irradiation
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A convenient method for the regioselective synthesis of unsaturated nucleoside analogs in water under microwave irradiation was developed. All pyrimidine and purine nucleoside derivatives were exclusively alkylated at N1 and N9 respectively in good to excellent yields. In addition, this system could tolerate a broad range of functional groups, such as chloro, bromo, iodo, alkyl, amino, and hydroxyl groups. More importantly, the reaction scale could be enlarged to 50 mmol which made this route attractive for industrial application.
- Xia, Ran,Sun, Li-Ping
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- 8-Bromination of 2,6,9-trisubstituted purines with pyridinium tribromide
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2,6,9-Trisubstituted purines are brominated in high yields using pyridinium tribromide as the brominating reagent. This procedure works excellently for electron-rich purines having electron-donating substituents at the 2- and 6-positions. The use of pyridinium tribromide, a crystalline alternative to elemental bromine, improves the bromination procedure for this type of substrate as the reagent is easy to handle and the work-up and purification procedures are simplified.
- Bliman, David,Pettersson, Mariell,Bood, Mattias,Gr?tli, Morten
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supporting information
p. 2929 - 2931
(2014/05/06)
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- Targeting cytotoxicity and tubulin polymerization by metal-carbene complexes on a purine tautomer platform
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This communication describes the synthesis, structural investigation and tubulin binding of purine rare imino-tautomer based Ag(i) and Hg(ii)-carbene complexes. These complexes exhibit cytotoxicity through tubulin interaction by binding to a site close to
- Khanna, Shruti,Jana, Batakrishna,Saha, Abhijit,Kurkute, Prashant,Ghosh, Surajit,Verma, Sandeep
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supporting information
p. 9838 - 9842
(2014/06/24)
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- Synthesis and anticonvulsant activity of novel purine derivatives
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A series of new purines containing triazole and other heterocycle substituents was synthesized and evaluated for their preliminary anticonvulsant activity and neurotoxicity by using the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and rotarod neurotoxicity (TOX) tests. Among the compounds studied, 9-decyl-6-(1H-1,2,4-triazol-1-yl)-9H-purine (5e) was the most potent compound, with a median effective dose of 23.4 mg/kg and a high protective index of more than 25.6 after intraperitoneal administration in mice. Compound 5e showed significant oral activity against MESinduced seizures in mice, with an ED50 of 39.4 mg/kg and a PI above 31.6. These results demonstrate that compound 5e possesses better anticonvulsant activity and is safer than the commercially available drugs carbamazepine and valproate in MES, scPTZ and TOX models.
- Wang, Shi-Ben,Jin, Peng,Li, Fu-Nan,Quan, Zhe-Shan
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p. 574 - 583
(2015/03/14)
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- Synthesis and evaluation of anticonvulsant and antidepressant activities of 7-alkyl-7H-tetrazolo[1,5-g]purine derivatives
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Seventeen 7-alkyl-7H-tetrazolo[1,5-g]purine derivatives were synthesized, and their anticonvulsant and antidepressant activities were evaluated in a mouse model. The anticonvulsant effect and neurotoxicity of the compounds were evaluated with a maximal electroshock test and a rotated test in mice, respectively. Most of the compounds had anticonvulsant activity; among the compounds studied, 7-(3-chlorobenzyl)-7H-tetrazolo[1,5-g]purine (3h) was found to be the most potent compound with a median effective dose (ED50) value of 28.9 mg/kg and a protective index value of 15.8, possessing better anticonvulsant activity and higher safety than the marketed drug carbamazepine. To explain the possible mechanism of anticonvulsant activity, compound 3h was tested in pentylenetetrazole-induced seizures tests, and the results suggest that compound 3h exerts anticonvulsant activity through a GABA-mediated mechanism. Forced swimming test showed that at a dose of 40 mg/kg, five compounds have significant antidepressant activity, the most active compound was 7-(2-chlorobenzyl)-7H-tetrazolo[1,5-g]purine (3g), which decreased immobility time by 56 %.
- Wang, Shi-Ben,Deng, Xian-Qing,Liu, Da-Chuan,Zhang, Hong-Jian,Quan, Zhe-Shan
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p. 4619 - 4626
(2016/02/20)
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- Synthetic studies on compounds related to aminoimidazolecarboxamide: Synthesis of angularly fused purine derivatives and a solid phase ring transformation (ANRORC) to imidazo [1,5-a] pyrazine
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l-Benzyl-5-aminoimidazole-4-carboxamide la has been used as a convenient precursor for the synthesis of new triazolo [3,4-i] purines 6 and the corresponding tetrazolo analogue 7. A mesoionic isomer 8 seems to exist along with 7. Interesting heteroaryl-purine motifs have also been prepared via suitably substituted 9-benzyIpurines. Imidazo |I,5-a| pyrazine derivative has been prepared in a solid phase exploitation of suitable imidazolium salt via ANRORC.
- Chattopadhyay, Gautam,Ray, Parlha Sinha
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p. 546 - 552
(2013/06/26)
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- Synthesis of some novel amino and thiotetrazole purine derivatives and investigation of their antimicrobial activity and DNA interactions
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A series of amino and thiotetrazole purine derivatives introduced with different alkyl groups in position 9 was synthesized. The structures of the synthesized compounds were characterized using spectroscopic methods. All the synthesized compounds were screened for their antibacterial activities against Gram-positive and Gram-negative bacteria and for their antifungal activities against yeast strains. The effect of the compounds on pBR322 plasmid DNA was studied by gel electrophoretic mobility measurements. The results of antimicrobial activity show that attachment of tetrazole group to purine bases results in disappearance of antimicrobial activity The results of the plasmid DNA interaction and the restriction studies suggest that while aminotetrazole purine derivatives cause DNA damages, thiotetrazole purine derivatives are believed to form a range of interstrand GG adducts with duplex DNA that induce global changes in the DNA conformation.
- Dilek Celik, Gulay,Disli, Ali,Oner, Yagmur,Acik, Leyla
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p. 1470 - 1479
(2013/03/29)
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- Highly efficient and broad-scope protocol for the preparation of 7-substituted 6-halopurines via N 9-Boc-protected 7,8-dihydropurines
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9-Boc-6-chloropurine, which can be obtained in high yield, is nearly quantitatively reduced with the THFBH3 complex. The obtained 9-Boc-7,8-dihydropurine derivative is more stable compared to the corresponding 9-tritylpurine and can be smoothly
- Kotek, Vladislav,Tobrman, Toma,Dvoak, Dalimil
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body text
p. 610 - 618
(2012/04/04)
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- Selective synthesis of 7-substituted purines via 7,8-dihydropurines
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A simple and efficient protocol for the preparation of 7-substituted purines is described. 6- and 2,6-Dihalopurines were N9-tritylated and then transformed to 7,8-dihydropurines by DIBAL-H. Subsequent N 7-alkylation followed by N9-trityl deprotection with trifluoroacetic acid was accompanied by spontaneous reoxidation, which led to the 7-substituted purines at 55 - 88% overall isolated yields.
- Kotek, Vladislav,Chudikova, Nadezda,Tobrman, Tomas,Dvorak, Dalimil
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scheme or table
p. 5724 - 5727
(2011/03/19)
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- Heteroaryl compounds useful as inhibitors of E1 activating enzymes
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This invention relates to compounds that inhibit E1 activating enzymes, pharmaceutical compositions comprising the compounds, and methods of using the compounds. The compounds are useful for treating disorders, particularly cell proliferation disorders, including cancers, inflammatory and neurodegenerative disorders; and inflammation associated with infection and cachexia.
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- Synthesis of a cyclic tetrameric purine by successive cross-coupling reactions and subsequent Pd-catalyzed cyclization
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The tetrameric N-benzyl-protected purine (quaterpurine) 2 was synthesized and characterized as its palladium complex [2Pd]. The synthesis commenced with the Pd-catalyzed cross-coupling of 8-zincated 9-benzyl-6-chloro-8- iodopurine (9) and 9-benzyl-6-iodopurine (11) establishing the first C-6/ C-8 bond. The sequence was repeated twice after iodo-dechlorination at C-6′ (C-6″) of the respective dimer 12 and trimer 15. The final ring closure was achieved at the tetrameric 6?-chloro-8-iodoquaterpurine 3b by a reductive intramolecular cross-coupling with hexamethylditin in the presence of Pd2(dba)3 and P(2-furyl)3. The overall yield in the eight step sequence was 17 % starting from 9-benzyl-6-chloropurine (8), the immediate precursor of 11. Other strategies to combine the purine fragments, i.e. by dimer/dimer bond formation or by regioselective cross-coupling, were not successful. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Guthmann, Holger,Koenemann, Martin,Bach, Thorsten
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p. 632 - 638
(2007/10/03)
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- Mitsunobu coupling of nucleobases and alcohols: An efficient, practical synthesis for novel nonsugar carbon nucleosides
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(Chemical Equation Presented) A simple facile synthesis of substituted purine derivatives has been developed by using Mitsunobu conditions for an alcohol and a respective nucleobase. A wide range of alcohols produces good to excellent yield (>90%). The resulting purine analogues show good regioselectivity with N-9 substitution as the dominant products in most of the cases. Application of diastereospecific alcohols reveals a complete inversion of the carbon stereogenic center giving a single diastereomer. More than two dozen novel nucleobase derivatives have been prepared in high yield.
- Lu, Weibing,Sengupta, Sujata,Petersen, Jeffrey L.,Akhmedov, Novruz G.,Shi, Xiaodong
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p. 5012 - 5015
(2008/02/07)
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- Synthesis and biological testing of purine derivatives as potential ATP-competitive kinase inhibitors
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On the basis of ATP adenine, a series of adenine and purine derivatives was prepared and tested for their ability to inhibit a spectrum of disease-related kinases. There has been scant research investigating the potential of cosubstrate derived kinase inhibitors for other kinases than CDKs. Our inhibitor design combined the purine system from the original cosubstrate ATP and phenyl moieties in order to explore possible interactions with the different regions of the ATP binding site in several disease-related protein kinases. There have been a number of hits for the assayed substances, which led us to conclude that the spectrum of compounds may prove to be a valuable tool kit for the evaluation of bonding and selectivity patterns for a wide variety of kinases.
- Laufer, Stefan A.,Domeyer, David M.,Scior, Thomas R. F.,Albrecht, Wolfgang,Hauser, Dominik R. J.
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p. 710 - 722
(2007/10/03)
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- Synthesis and biological activity of novel substituted pyridines and purines containing 2,4-thiazolidinedione
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A series of substituted pyridines and purines containing 2,4-thiazolidinedione were designed and synthesized from their corresponding pyridines and purines. These synthesized compounds (entry no. 6a-d, 12a-e, 18a-d, 23a-c) were evaluated for their effect on triglyceride accumulation in 3T3-L1 cells in vitro and their hypoglycemic and hypolipidemic activity in the genetically diabetic KKAy mice in vivo. On the basis of their biological activities, 5-(4-{2-[N-methyl-(5-phenyl-pyridin-2-yl)amino]ethoxy} benzyl)thiazolidine-2,4-dione (6d) was selected as a candidate for further pharmacological studies.
- Kim, Bok Young,Ahn, Joong Bok,Lee, Hong Woo,Kang, Sung Kwon,Lee, Jung Hwa,Shin, Jae Soo,Ahn, Soon Kil,Hong, Chung Il,Yoon, Seung Soo
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p. 433 - 447
(2007/10/03)
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- Design, synthesis and structure-activity relationships of a series of 9-substituted adenine derivatives as selective phosphodiesterase type-4 inhibitors
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Adenine derivatives substituted in position 9 have been demonstrated to have potent cyclic nucleotide phosphodiesterase (PDE) inhibition properties with high selectivity toward PDE-4. Starting from our initial lead compound 9-(2-fluorobenzyl)-N6-methyl-2-trifluoromethyladenine (4, NCS613), we designed and synthesized a new series of 9-substituted derivatives for developing structure-activity relationship studies. This new series of derivatives showed increased potencies and better selectivity profiles. Structural modifications were achieved in parallel on three different positions of the adenine ring, and led to the following observations: (i) introduction of a lipophilic substituent such as trifluoromethyl, n-propyl group or iodine in the C-2 position is favourable for both the PDE-4 inhibitory activity and the selectivity towards other isoenzymes; (ii) functionalization of the N9 benzyl group with a 2-methoxy substituent led to remarkably more active compounds; (iii) replacement of the N6-methylamino moiety by other amino groups is detrimental to the activity. Among all derivatives prepared, the 9-(2-methoxybenzyl)-N6-methyl-2-trifluoromethyladenine (9r), 9-(2-methoxybenzyl)-N6-methyl-2-n-propyladenine (9s), and the 2-iodo-9-(2-methoxybenzyl)-N6-methyladenine (13b) were found to be the most potent inhibitors within this series (PDE-4-IC50=1.4, 7.0, and 0.096 nM, respectively). Compared to our reference compound 4, which showed an IC50 of 42 nM, the derivative 13b was found 450-fold more potent. Moreover, 2-iodo-9-(2-methoxybenzyl)-N6-methyladenine (13b) and 9-(2-methoxybenzyl)-N6-methyl-2-trifluoromethyladenine (9r), were at least 50 000-150 000 times more selective for the PDE-4 than for the other PDE families. Additionally, these new derivatives showed improved efficiency in inhibiting the TNFα release from mononuclear cells from healthy subjects (e.g. adenines 7l, 9s and 13b). Thus, compounds 7l, 9r, 9s and 13b are among the most potent and selective PDE-4 inhibitors reported so far and represent very promising pharmacological tools for a better understanding of the signal transduction involving cyclic AMP within the cell: this pathway is implicated in the physiology and the pathophysiology of inflammation, asthma and autoimmune disorders.
- Raboisson, Pierre,Lugnier, Claire,Muller, Christian,Reimund, Jean-Marie,Schultz, Dominique,Pinna, Guillaume,Le Bec, Alain,Basaran, Helene,Desaubry, Laurent,Gaudiot, Francois,Seloum, Mohamed,Bourguignon, Jean-Jacques
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p. 199 - 214
(2007/10/03)
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- A Facile Synthesis of Trifluoromethylamines by Oxidative Desulfurization-Fluorination of Dithiocarbamates
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Trifluoromethylamines are easily synthesized from dithiocarbamates by a reagent system consisting of tetrabutylammonium dihydrogentrifluoride and an N-halo imide under mild conditions. When this reaction was applied to dithiocarbamates ArN(R)CS2Me at higher temperatures, the trifluoromethylation was accompanied by halogen substitution at the p-position of the Ar group. The synthesis of trifluoromethyl-substituted adenosine is also described.
- Kanie, Kiyoshi,Mizuno, Katsuya,Kuroboshi, Manabu,Hiyama, Tamejiro
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p. 1973 - 1991
(2007/10/03)
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- 6-Halopurines in palladium-catalyzed coupling with organotin and organozinc reagents
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N-9 and N-7 benzylated 6-halopurines readily participate in palladium catalyzed cross coupling reactions with organotin and organozinc derivatives. In most instances the 6-chloropurines can be used. Organostannanes are excellent reagents for the introduction of alkenyl and aryl substituents, but organozinc compounds are the reagents of choice for the introduction of alkyl groups.
- Gundersen,Bakkestuen,Aasen,Overas,Rise
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p. 9743 - 9756
(2007/10/02)
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- ORGANIC SYNTHESIS USING ORGANOSULFUR-NITRITES AND -NITRATES
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Thionitrites or thionitrates have been considered to be unstable.However, bulky groups' thio-NOn such as t-butylthio-nitrites and -nitrates have been readily synthesized and found to be stable enough for the use of the useful organic syntheses as an excellent nitrosation and diazotization reagents under mild conditions.Direct conversion of amines to the corresponding halides in the presence of copper halides (II), fluorination of heterocyclic amines in the presence of sodium tetrafluoroborate, α- oximation of methylene groups in ketones, facile cleavage of C=N bond to ketones, and desulfurization of thioacetals and thioketals, and other useful organic syntheses are described.
- Kim, Yong Hae
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p. 249 - 260
(2007/10/02)
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- Mitsunobu reactions for the synthesis of carbocyclic analogues of nucleosides: Examintion of the regioselectivity
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In order to provide a general synthetic method for carbocyclic nucleosides, regioselectivities in Mitsunobu reaction of purine, pyrimidin-2-one and their substituted derivatives with a variety of alcohols with a variety of alcohols were examined and found to depend upon both substituents of the bases and kind of the alcohols.
- Toyota,Katagiri,Kaneko
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p. 1295 - 1305
(2007/10/02)
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- 6-(Alkylamino)-9-benzyl-9H-purines. A New Class of Anticonvulsant Agents
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Several 9-alkyl-6-substituted-purines were synthesized and tested for anticonvulsant activity against maximal electroshock-induced seizures (MES) in rats.Most compounds were prepared in three steps from 5-amino-4,6-dichloropyrimidine or in two steps via alkylation of 6-chloropurine.Potent anticonvulsant activity against MES resided in compounds that contain a benzyl substituent at the 9-position of 6-(methylamino)- or 6-(dimethylamino)purine.Among commonly used agents for control of seizures, this type of structure represents a new class of potent anticonvulsant agents.
- Kelley, James L.,Krochmal, Mark P.,Linn, James A.,McLean, Ed W.,Soroko, Francis E.
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p. 606 - 612
(2007/10/02)
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- ALKYLATION OF SOME 6-SUBSTITUTED PURINES UNDER INTERPHASE CATALYSIS CONDITIONS
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The mixture of 9-, 3-, and 7-benzyl-6-substituted purines is formed in almost quantitative yield by the alkylation of 6-benzylamino-, 6-furfurylamino-, 6-methylthio-, and 6-chloropurine with benzyhalides in the biphasic system of the liquid-liquid or liquid-solid type in the presence of interphase catalysts (quarternary ammonium salts, 18-crown-6).The catalytic activity of the quarternary ammonium salts increases with the inrease in the lipophilicity of the cation.Taking the alkylation of 6-benzylaminopurine as an example, the possibility of the application of ''triphasic catalysis'' in the alkylation reaction of purines is indicated.The alkylation of 6-substituted purines with isopropylbromide proceeds regioselectively under the conditions of the interphase catalysis with the formation of the corresponding 9-isopropylpurines.
- Ramzaeva, N. P.,Goncharova, L. N.,Lidak, M. Yu.,Gol'dberg, Yu. Sh.,Shimanskaya, M. V.
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- Heterocyclic Ambident Nucleophiles. III* The Alkylation of Sodium Adenide
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The alkylation of sodium adenide in HCONMe2 (30 deg) with various alkylating agents was analysed by 1H n.m.r. spectroscopy.Widely varying N3:N7:N9 alkylation patterns were observed, depending on the alkylating agent.These patterns are interpreted in terms of the electrostatic, thermodynamic and steric factors involved in the different SN2 transition states appropriate to each alkylating agent.Hydrogen bonding association between the 6-amino group and certain carbonyl containing alkylating agents is proposed to explain the enhancedN7-alkylation in some cases.Support for this latter proposal was obtain from a comparison of the adenine alkylation results with the corresponding alkylation patterns of 6-pivaloylamino- and 6-chloro-purine.
- Rasmussen, Malcolm,Hope, Janet M.
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p. 525 - 534
(2007/10/02)
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- Heterocyclic Ambident Nucleophiles. IV* The alkylation of Metal Salts of Adenine
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The N3:N7:N9 alkylation patterns for reactions of the lithium, sodium, and potassium salts of adenine with various alkylating agents in dimethyl sulfoxide were determined by 1H n.m.r. spectroscopy.Only for the Li+ salt was any significant effect of ionic association noticed.Of the alkylating agents used, only chloromethyl pivalate gave a concentration dependent alkylation pattern.The latter effect was most pronounced with the heterogenous alkylation conditions of anhydrous Na2CO3/HCONMe2, adenine, and chloromethyl pivalate; here, increasingconcentrations changed the main reaction from N7- to N9-alkylation.Solvent effects on the alkylation patterns were also studied.Within the common dipolar aprotic solvent group, (Me2N)3PO, HCONMe2 and Me2SO, effects were small; in protic solvents, particularly formamide, enhanced N3-alkylation was observed.
- Rasmussen, Malcolm,Hope, Janet M.
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p. 535 - 542
(2007/10/02)
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- Coupling of Diazopurines, a Curious Steric Effect in a Free Radical Reaction
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The reaction of adenine derivatives with nitrite esters in the presence of arenes was examined and found to give 6-arylpurines in good (83percent) to poor (11percent) yield.The arylated products consisted only of the meta and para isomers; none of the anticipated ortho isomers were found.The predominance of meta- and para-substituted products is attributed to steric effects.The evidence that the reaction proceeds via a purine radical includes light stimulation, relative insensitivity to electronic factors, and the facile reaction of the purine intermediate with pyridine N-oxide.Photolysis of 6-iodo-9-benzylpurine in the presence of anisole gave the same mixture of 6-(m-methoxyphenyl)- and 6-(p-methoxyphenyl)purine as did diazotization, suggesting that both reactions involve the same purine radical.
- McKenzie, Thomas C.,Epstein, Joseph W.
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p. 4881 - 4884
(2007/10/02)
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- O-Acylation using organothallium compounds
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Thallous salts of β-dicarbonyl compounds, prepared by reaction of the β-dicarbonyl compounds with a thallous alkoxide, are treated with alkyl halides to give C-alkyl products in high yield, with acyl halides at room temperature to give C-acyl products, and with acyl halides at low temperatures to give O-acyl products. Thallous phenolates are esterified with acyl or aroyl halides. Anhydrides are also prepared, as are biaryls and bi-sec-alkyls. N-Heterocyclics, including purines and pyrimidines, are N-alkylated. Lactams are O-acylated or N-alkylated.
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