Application of primary allyl amines from Morita-Baylis-Hillman adducts: Cyanogen-azide-mediated synthesis of substituted 5-aminotetrazoles and their attempted transformation to tetrazolo[1,5-a]pyrimidinones

Abstract

A general protocol for the synthesis of substituted 5-aminotetrazoles by reacting cyanogen azide with the primary allyl amines afforded either by SN2 or SN2′- reaction of Morita- Baylis-Hillman acetate of acrylate has been developed. The base-promoted intramolecular cyclization of these tetrazoles afford highly substituted 2-azido-pyrimidin-4(3H)-ones instead of the expected tetrazolo-pyrimidinone 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 respective 2-azido-pyrimidin-4(3H)-ones via crystallization. The structure of tetrazolo[1,5-a]pyrimidin-7(4H)-one has been unambiguously assigned via X-ray crystallography analysis. The existence of azide-tetrazole tautomerism in this class of compounds has been supported through NMR studies.