How is 4-Hydrazino-5-phenylthieno[2,3-d]pyrimidine (CAS: 113246-86-9) typically synthesized?

4-Hydrazino-5-phenylthieno[2,3-d]pyrimidine is synthesized through a multi-step process involving the formation of a thieno[2,3-d]pyrimidine derivative, followed by hydrazinolysis. This typically requires the use of hydrazine as a reagent and may involve the use of catalysts such as palladium or other transition metals. The reaction is usually conducted under basic conditions and yields up to 75-85% depending on the conditions.