A new route for the synthesis of pyrimido[2,1-b][1,3]thiazine ring system

Abstract

A simple and efficient pathway to conjugate monosaccharides to thienopyrimidines via click chemistry establishing a 1,2,3-triazole linker was reported. Potential pharmaceutical interest is envisaged for the expected target products. Starting from a 2-isothiocyanate-thiophene-3-carboxylate, an allylthiourea was obtained with allylamine, cyclized and S-propargylated to give a thienopyrimidine-alkyne core. Click reaction with tetraacetyl-1-azidoglucose was successful to give the target conjugate with one sugar unit. When propargylamine was used in the first step, the expected thiourea cyclized via the alkyne moiety leading to pyrimido[2,1-b][1,3]thiazine.