How is (S)-1-methyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol (CAS: 27740-96-1) typically synthesized?

(S)-1-methyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol is synthesized via a multi-step process involving the reduction of isoquinoline-6,7-dione followed by methylation. Common methods include the use of lithium aluminum hydride (LAH) for reduction and methyl iodide with sodium hydride as a catalyst. The yield is typically around 70-80%, depending on the reaction conditions and purification steps.