Application of Primary Allylamines from Morita–Baylis–Hillman Adducts: Cyanogen Azide Mediated Synthesis of Substituted 5‐Aminotetrazoles and Their Attempted Transformation into Tetrazolo[1,5‐a]pyrimidinones

Abstract

AbstractA general protocol for the synthesis of substituted 5‐aminotetrazoles by treating cyanogen azide with primary allylamines afforded either by SN2 or SN2′ reactions of Morita–Baylis–Hillman acetates of acrylate has been developed. The base‐promoted intramolecular cyclizations of these tetrazoles afford highly substituted 2‐azidopyrimidin‐4(3H)‐ones instead of the expected tetrazolopyrimidinone due to azide–tetrazole tautomerism. Nevertheless it has been discovered that substituted tetrazolo[1,5‐a]pyrimidin‐7(4H)‐ones could be isolated in pure form from a methanolic solution of the respective 2‐azidopyrimidin‐4(3H)‐ones through crystallization. The structure of tetrazolo[1,5‐a]pyrimidin‐7(4H)‐one was unambiguously assigned by X‐ray crystallography. The existence of azide–tetrazole tautomerism in this class of compounds has been supported through NMR spectroscopic studies.