Benzyl Bromide → 2-Benzyl-6-bromo-2H-indazole

Temperature

120 °C

6-Bromoindazole (14.42 g, 73.2 mmol) was suspended in 50 mL of dioxane and the mixture was treated with benzyl bromide (10.5 mL, 88.8 mmol) and then heated in an oil bath to 120° C. with mechanical stirring overnight. The resulting thick suspension was allowed to cool to 80° C. (bath temp) and 200 mL of EtOAc was added. The mixture was vigorously stirred for 20 minutes and the precipitated orange-brown solid was collected by filtration, washed well with EtOAc and air-dried. The resulting brown solid was partitioned between sat aq. NaHCO3 (100 mL) and EtOAc (300 mL) with stirring until all of the solid material had dissolved. The layers were separated and the aqueous phase was extracted with 2×100 mL of EtOAc. The combined organic phases were washed with brine, dried and filtered and concentrated in vacuo to give a brown solid. Recrystallization of the solid from 200 mL of 2:1 EtOH:water gave 12.78 g (61%) of desired product as tan needles. 1H-NMR (DMSO-d6) 8.55 (s, 1H), 7.84 (s, 1H), 7.72 (d, 1H), 7.48-7.28 (m, 5H), 7.13 (d, 1H), 5.62 (s, 2H); LC-MS [M+H]+=287.3, 289.0, RT=3.53 min.

1. additionwas added
2. stirringThe mixture was vigorously stirred for 20 minutes
3. filtrationthe precipitated orange-brown solid was collected by filtration
4. washwashed well with EtOAc
5. customair-dried
6. customThe resulting brown solid was partitioned
7. stirringwith stirring until all of the solid material
8. dissolutionhad dissolved
9. customThe layers were separated
10. extractionthe aqueous phase was extracted with 2×100 mL of EtOAc
11. washThe combined organic phases were washed with brine
12. customdried
13. filtrationfiltered
14. concentrationconcentrated in vacuo
15. customto give a brown solid
16. customRecrystallization of the solid from 200 mL of 2:1 EtOH

ORD record

ord-d8926362a6d9423e8542f26e6f0291a4

Source dataset

uspto-grants-2013_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08431695B2