Yield:4160-61-6 99.9%

Reaction Conditions:

with sodium hydride in tetrahydrofuran;

Steps:

F Step F Synthesis of 4-Oxotetrahydro-2-indole-thiopyran-3-carboxylic acid methyl ester (a1)

2.7098 g of NaH (60%) was added to a 250 mL dry three-necked flask, and 40 mL of anhydrous tetrahydrofuran (THF) was added and stirred at room temperature for 10 min.Then, a solution of dimethyl 3,3'-thiodipropionate (10.1015 g, 0.049 mol) in THF (30 mL) was slowly added dropwise, and the addition was completed in about 1 h.Then, 10 mL of THF was added to rinse the dropping funnel, and the reaction was continued for 1-2 hours, and the reaction was completed. The reaction solution was adjusted to pH 6-7 with 2% dilute hydrochloric acid, then extracted with dichloromethane (50 mL*3), and the organic layer was combined and washed with saturated sodium chloride solution (50 mL*3), and the organic layer was collected and added. The sodium sulfate is dried and filtered.The filtrate was decompressed to remove the solvent.Yellow oily liquid 8.52,Yield 99.9%

References:

CN109280048,2019,A Location in patent:Paragraph 0056; 0093; 0094