Ethylenediamine → 6-cyclopropyl-1H-indazole

In a round-bottomed flask, 6-cyclopropyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-indazole (668 mg, 2.2 mmol) was dissolved in dichloromethane (12 ml) and trifluoroacetic acid (6.5 ml, 84.4 mmol) was added. The yellow reaction mixture was stirred at room temperature for 2.25 h then concentrated. The residue was redissolved in dichloromethane (12 ml) and ethylenediamine (9.0 ml, 133 mmol) was added. The solution was stirred at room temperature for 1 h then quenched with water and extracted with EtOAc (2×). The combined organic layers were washed with water and brine then dried over sodium sulfate, filtered and concentrated. The residue was chromatographed over silica gel with EtOAc/Hexanes (gradient 0-25% EtOAc) to provide 317 mg (91%) of 6-cyclopropyl-1H-indazole as a light yellow solid. 1H NMR (CDCl3, 300 MHz): δ (ppm) 7.99-8.08 (m, 1H), 7.59-7.70 (m, 1H), 7.16-7.25 (m, 1H), 6.88-7.01 (m, 1H), 1.94-2.14 (m, 1H), 0.96-1.11 (m, 2H), 0.71-0.84 (m, 2H).

1. concentrationthen concentrated
2. dissolutionThe residue was redissolved in dichloromethane (12 ml)
3. stirringThe solution was stirred at room temperature for 1 h
4. customthen quenched with water
5. extractionextracted with EtOAc (2×)
6. washThe combined organic layers were washed with water and brine
7. dry with materialthen dried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated
10. customThe residue was chromatographed over silica gel with EtOAc/Hexanes (gradient 0-25% EtOAc)

ORD record

ord-9284a59638b84a918f03ba45fdab7d78

Source dataset

uspto-grants-2014_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08658646B2