How is Mirodenafil dihydrochloride (CAS: 862189-96-6) typically synthesized?

Mirodenafil dihydrochloride is synthesized through a multi-step process involving the protection of a hydroxyl group, followed by the formation of an amide bond, and subsequent deprotection and acidification to form the dihydrochloride salt. The synthesis involves the use of protecting agents like tert-butyldimethylsilyl chloride and deprotection using fluoride salts. The overall yield is around 70-75%, and the product is typically purified by recrystallization from ethanol.