start-ver=1.4
cd-journal=joma
no-vol=
cd-vols=
no-issue=24
article-no=
start-page=4167
end-page=4179
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2008
dt-pub=20080710
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=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
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=<p>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.</p>

en-copyright=
kn-copyright=

en-aut-name=IslamRafiqul
en-aut-sei=Islam
en-aut-mei=Rafiqul
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=NagamatsuTomohisa
en-aut-sei=Nagamatsu
en-aut-mei=Tomohisa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=
kn-affil=Department of Drug Discovery and Development, Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutica?l Sciences, Okayama University

affil-num=2
en-affil=
kn-affil=Department of Drug Discovery and Development, Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutica?l Sciences, Okayama University
en-keyword=8-azaxanthines
kn-keyword=8-azaxanthines
en-keyword=triazolopyrimidines
kn-keyword=triazolopyrimidines
en-keyword=regioselectivity
kn-keyword=regioselectivity
en-keyword=alkylations
kn-keyword=alkylations
en-keyword=heterocycles
kn-keyword=heterocycles
END