New synthesis of 6,8-diamino-substituted pyrano[3,4-c]pyridines from related pyrano[3,4-c]pyridin-6-one

The tosylation of 3,3-dimethyl-8-(morpholin-4-yl)-6-oxo-3,4,6,7-tetrahydro-1H-pyrano[3,4-c]pyridine-5-carbonitrile with TsCl occurs at the oxo group of the NH-lactam moiety. The subsequent nucleophilic displacement of O-tosylate by various amines affords the title compounds in good yields.