Boron difluoride complexes of carbamoyl Meldrumʹs acids

5-[Hydroxy(aryl/alkylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones react with BF3·Et2O in mild conditions leading to the formation of boron difluoride complexes of carbamoyl Meldrumʹs acids. The X-ray structure has been obtained for one representative complex. The obtained new compounds are air and moisture stable at standard ambient conditions and easily isolable.