5-Triazolyluracils and Their N1-Sulfonyl Derivatives: Intriguing Reactivity Differences in the Sulfonation of Triazole N1'-Substituted and N1'-Unsubstituted Uracil Molecules

Saftić, Dijana; Vianello, Robert; Žinić, Biserka (2015) 5-Triazolyluracils and Their N1-Sulfonyl Derivatives: Intriguing Reactivity Differences in the Sulfonation of Triazole N1'-Substituted and N1'-Unsubstituted Uracil Molecules. European Journal of Organic Chemistry (35). pp. 7695-7704. ISSN 1434-193X

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Abstract

We describe the synthesis of novel C5-triazolyl derived N1-sulfonylpyrimidines through CuI-catalyzed alkyne–azide cycloaddition followed by sulfonylation of the formed C5-triazolyl derivatives with various sulfonyl chlorides under basic conditions. In the latter step, an intriguing difference in the reactivity of the pyrimidine N1 was observed that depended on the nature of the substituent at a distant triazole N1' site. The N1' unsubstituted compounds gave very small amounts of sulfonylation products, whereas N1'-substituted systems produced high yields of the respective N1-sulfonyl-5-(1,2,3-triazol-4-yl)uracils. Computational analysis revealed a close correlation between the strength of the employed base catalysts and their abilities to increase the nucleophilicity of the uracil N1 atom through subsequent deprotonation, leading to more products. Following this step, the phosphazene tBu–P4 superbase was applied in the sulfonylation, resulting in exclusive formation of the triazole N1'-unsubstituted N1-sulfonylpyrimidines.

Item Type:	Article
Additional Information:	Financial support from the Croatian Science Foundation (grant number HRZZ-1477) is gratefully acknowledged. R. V. gratefully acknowledges the European Commission for an individual FP7 Marie Curie Career Integration Grant (contract number PCIG12-GA-2012-334493)
Uncontrolled Keywords:	nucleobases; sulfonylation; substituent effects; regioselectivity; density functional calculations
Subjects:	NATURAL SCIENCES NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Theoretical Chemistry NATURAL SCIENCES > Chemistry > Organic Chemistry
Divisions:	Division of Organic Chemistry and Biochemistry
Projects:	Project title Project leader Project code Project type Višenamjensko očitavanje DNA / RNA sekundarne strukture molekularnim kemijskim senzorima-DNA/RNA-MolSense Ivo Piantanida IP-2013-11-1477 HRZZ European Commision UNSPECIFIED PCIG12-GA-2012-334493 UNSPECIFIED
Depositing User:	Dijana Pavlović Saftić
Date Deposited:	02 May 2018 12:51
URI:	http://fulir.irb.hr/id/eprint/4019
DOI:	10.1002/ejoc.201501088

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