Yield:773136-66-6 94.9%

Reaction Conditions:

with sulfuric acid at 100; for 5 h;

Steps:

1.1 (1) Compound 2 synthesis method:

Compound 1 (20.0 g, 75.2 mmol, 1 eq) was dissolved in 70 mL of EtOH.Then gradually add H2SO4 (7.37g, 75.1mmol, 4.01mL, 1eq).The mixture was stirred at 100 ° C for 5 h.And use TLC (Dichloromethane/Methanol=10/1, Rf=0.87) The progress of the reaction was detected.When the reaction is complete,The reactants were concentrated under reduced pressure.The concentrated product was extracted (EOtOH 200 mL, NaHCO 3 saturated solution (100.0 mL x 2), and then the organic layer was taken.It was dried by adding anhydrous Na2SO4.After further evaporation to dryness the title product 2 (21.0 g, 71.4 mmol, 94.9% yield).Figure 3 shows the results of TLC chromatography for this reaction.

References:

CN109942582,2019,A Location in patent:Paragraph 0057-0061