The Sandmeyer Reaction on Some Selected Heterocyclic Ring Systems: Synthesis of Useful 2-Chloroheterocyclic-3-carbonitrile Intermediates

Abstract: The Sandmeyer reaction on some selected heterocyclesbearing the 2-amino-3-carbonitrile structural moiety has been in-vestigated in order to prepare the corresponding 2-chloro-3-carbo-nitrile derivatives as synthetic useful intermediates for furtherdevelopment. Key words: Sandmeyer reaction, 2-amino(heterocyclic)-3-carbo-nitriles, 2-aminopyrazoles, 2-aminooxazoles, 2-amino-4 H -pyrans,2-amino-1,4-dihydropyridines, 2-aminopyridines, 2-chloro(hetero-cyclic)-3-carbonitriles In the context of a current project in progress in our labo-ratory for the synthesis of pharmacological active com-pounds, 1 we have recently synthesized some differentlysubstituted 2-chloropyridine-3-carbonitrile intermediates I by Sandmeyer reaction 2 of easily available 2-aminopyri-dine derivatives II (Scheme 1). Eventually, intermediates I could also be prepared by reaction with sodium nitrite inhydrochloric acid, 3 or by reaction with phosphorus oxy-chloride from 2-pyridones III . 4 Scheme 1 2-Chloro(heterocyclic)-3-carbonitriles are well known,useful synthetic intermediates in heterocyclic chemistrythat have been transformed into complex and more ad-vanced heterocyclic compounds.