Direct Arylation of Adenine by Fluoro- and Chloronitrobenzenes: Effect of Microwaves

Abstract

Direct arylation of adenine with fluoro- and chloronitrobenzenes leads to mixtures of N9 and N7 substituted adenines. After separation by column chromatography, the individual isomers can be efficiently hydrogenated on Pd to give the corresponding aminophenyladenines. A significant enhancement of the reaction rate by microwave irradiation was observed. This two-step procedure was found to be a feasible route to otherwise hardly available 7-aminophenyladenines. Correlation between calculated shielding constants and experimental values of chemical shifts in ¹³C and ¹⁵N NMR was used for assignment of the site of substitution.

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GRAPHICAL ABSTRACT

Keywords:

• Chemoselectivity
• microwave chemistry
• N-arylation
• purines

ACKNOWLEDGMENT

Financial support of this work by grant No. 20/2013 (specific university research) from the Ministry of Education, Youth and Sports of the Czech republic is gratefully acknowledged.