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 | Zendy

Tomohisa Nagamatsu | Zendy; Rafiqul Islam | Zendy

Open Access

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

Author(s) -

Tomohisa Nagamatsu,

Rafiqul Islam

Publication year - 2006

Publication title -

synthesis

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.885

H-Index - 140

eISSN - 1437-210X

pISSN - 0039-7881

DOI - 10.1055/s-2006-950337

Subject(s) - alkylation , chemistry , dimethyl sulfate , alkyl , pyrimidine , regioselectivity , reagent , potassium carbonate , substituent , medicinal chemistry , ring (chemistry) , organic chemistry , stereochemistry , catalysis

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.

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