Formaldehyde → 7-Bromo-2-methyl-2H-indazole-3-methanol

Temperature

2.5 °C

To a solution of 7-bromo-2-methyl-2H-indazole (6: R=Me; 0.578 g, 2.93 mmol) in 15 mL of THF at −78° C. was added a 2.0 M solution of lithium diisopropylamide in tetrahydrofuran/heptane/ethylbenzene (1.8 mL, 3.6 mmol). The yellow-orange solution was stirred at 0-5° C. for 15 m, then rechilled to −78° C. for 15 m. Paraformaldehyde (0.92 g) was added, and the orange mixture was rapidly stirred at −78° C. for 75 m then at room temperature for 100 m. The mixture was loaded onto silica gel and concentrated. Column chromatography (0→66% EtOAc/hexanes) afforded 0.662 g of impure (7-bromo-2-methyl-2H-indazol-3-yl)-methanol (14a).

1. customrechilled to −78° C. for 15 m
2. stirringthe orange mixture was rapidly stirred at −78° C. for 75 m
3. customat room temperature
4. concentrationconcentrated

ORD record

ord-e6a56ffb61384ef388792ce4970a8650

Source dataset

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07365211B2