Convenient Synthesis of Fluorescent Chromeno[4,3-d]pyrimidines from Electron-Deficient 3-Vinylchromones

We report an easy and powerful approach to the synthesis of novel chromeno[4,3- d]pyrimidine-5-acetic acids through ANRORC reaction of electron-deficient 3-vinylchromones and 1,3-N,N-binucleophiles. The reaction proceeds under mild conditions (EtOH, rt) and is applicable to a wide range of substrates. The described compounds show fluorescence in the violet-blue range (390-460 nm) with Stokes shift of 40-80 nm and moderate quantum yield (0.15-0.20). As the electron-withdrawing group is conserved in the form of an acetic acid fragment, these compounds may readily be functionalized or conjugated to a required substrate for (bio)analytical purposes.