Indole → 2,3-dihydro-7H-[1,4]dioxino[2,3-e]indole-9-carboxylic acid

関与物質

反応手順

To a stirred solution of compound 1 (25.000 g, 162.19 mmol) and methyl-2-azidoacetate (63.17 mL, 648.8 mmol) in dry MeOH (350.0 mL) at −10° C., was added a solution of NaOMe (35.046 g, 648.76 mmol) in MeOH (400.0 mL). The reaction mixture was stirred at the same temperature for 3 h and then rt for 16 h. The reaction progress was monitored by diluting an aliquot of the reaction mixture with water and extracting with EtOAc. The organic layer was spotted over an analytical silica gel TLC plate and visualized using 254 nm UV light. The reaction progressed to completion with the formation of a non-polar spot. The Rf values of the starting material and product were 0.3 and 0.4, respectively. The reaction mixture was poured into saturated aqueous NH4Cl solution (150.0 mL) and extracted with Et2O (2×500.0 mL). The organic layer was dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford crude compound 2 as a brown liquid. The crude compound was directly used in the next step without purification. TLC system: 30% EtOAc in petroleum ether. Yield 25.000 g (crude).

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