2278-11-7Relevant academic research and scientific papers
Synthesis and regioselective N- and O-alkylation of 1H- or 3H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7(4H,6H)-diones (8-azaxanthines) and transformation of their 3-alkyl derivatives into 1-alkyl isomers
Islam, Rafiqul,Nagamatsu, Tomohisa
, p. 4167 - 4179 (2008/03/13)
Several alkylating agents, for example alkyl halides and dimethyl sulfate, were employed in aprotic solvents under a variety of conditions for the alkylation of mono- and disubstituted 1H- or 3H-[1,2,3]triazolo[4,5-d] pyrimidine-5,7(4H,6H)-diones, which were prepared by cyclization of the appropriate 5,6-diaminouracils with nitrous acid. The alkylation on the triazole ring in the presence of anhydrous potassium carbonate took place simultaneously at the 1- and 2-positions, with alkylation at the 2-position taking priority. Similar alkylation on the pyrimidine ring with an equivalent alkylating reagent took place only at the 4-position. The alkylation of 3,6-disubstituted derivatives at room temperature led to 5-O-alkylation accompanied by 4-N-alkylation, but at high temperature only 4-N-alkylation took place. Reaction of 3,4,6-trisubstituted derivatives with excess alkylating agent at high temperature leads to the formation of 1,4,6-trisubstituted derivatives with elimination of the 3-substituent. Georg Thieme Verlag Stuttgart.
Regioselective N- and O-Alkylation of 3H-[1,2,3]triazolo-[4,5-d]pyrimidine-5,7(4H,6H)-diones (8-azaxanthines) and transformation of 3-alkyl derivatives into 1-alkyl isomers
Nagamatsu, Tomohisa,Islam, Rafiqul
, p. 1811 - 1820 (2007/10/03)
The alkylation on the pyrimidine ring of 3-methyl-3H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7(4H,6H)-diones (1) with an equimolecular amount of alkylating agent in the presence of anhydrous potassium carbonate in aprotic solvents under heating took place only
Study of the Prototropic Tautomerism of 8-Azatheophylline by 13C and 15N NMR Spectroscopy
Gerrit, L'abbe,Persoons, Marie-Anne,Toppet, Suzanne
, p. 362 - 364 (2007/10/02)
Comparison of the 13C and 15N NMR spectra of 8-azatheophylline with those of its three methylated derivatives and other model compounds from the literature showed that 8-azatheophylline exists to the extent of 80percent in the N-2 tautomeric form in DMSO solution. KEY WORDS 13C NMR 15N NMR Prototropism 4,6-Dimethyl-5,7-dioxo-1,2,3-triazolopyrimidine
ISOMERIZATION AND DEALKYLATION OF METHYLATED XANTHINIUM DERIVATIVES
Muravich-Aleksandr, Kh. L.,Kolesova, M. B.,Pernikova, V. G.,Smirnova, N. V.
, p. 562 - 567 (2007/10/02)
The isomerization or dealkylation of methylated xanthinium derivatives takes place with the participation of nucleophiles and is facilitated in the presence of a sterically hindered configuration.When heated, 7,9-dimethyl- and 1,7,9-trimethylxanthinium salts isomerize to theobromine and caffeine respectively.Under these conditions 3,7,9-trimethyl- and 1,3,7,9-tetramethylxanthinium salts are dealkylated.The 1,7,9- and 3,7,9-trimethylxanthinium betaines are isomerized quantitatively to caffeine.The role of the nucleophile under these conditions is played by the negatively charged fragment in the pyridine part of molecule.An intermolecular mechanism of rearrangement of the 3,7,9-trimethylxanthinium betaine is demonstrated.The sterically overloaded 1,3,8,9-tetramethylxanthine and 1,3,9-trimethyl-8-azaxanthine and not the charged compounds undergo rearrangement.In these cases the nucleophilic center is the doubly bonded N7 atom in the five-membered ring.
SYNTHESIS AND THERMAL TRANSFORMATIONS OF QUATERNARY SALTS IN THE SERIES OF 5,7-DIOXOTETRAHYDRO-vic-TRIAZOLOPYRIMIDINE (8-AZAXANTHINE)
Kolesova, M. B.,Muravich-Aleksandr, Kh. L.,Smirnova, N. V.,Girshovich, M. Z.
, p. 954 - 960 (2007/10/02)
The quaternization of methyl derivatives of 8-azaxanthine by various alkylating agents was studied.These compounds form two series of quaternary salts, i.e., 7,8- and 7,9-dimethyl-8-azaxanthinium.When heated, all the quaternary salts undergo rearrangement
