A method of synthesis of 1,1′-(alkanediyl)bis{3-cyano-4-[4,5,5-trimethyl-2-oxo-5H-furan-3-yl]-pyridin-2(1H)-ones} from the corresponding lactones is developed. The synthesized compounds undergo intramolecular cyclization to form symmetrical 7,7′-(alkanediyl)bis{5-amino-3,3-dimethylfuro[3,4-f]isoquinoline-1,6(3H,7H)-diones}.