2,2,6,6-Tetramethylpiperidine → 1-(4-chlorophenyl)-5-tributylstannyl-1H-pyrazole

Temperature

-78 °C

2,2,6,6-Tetramethylpiperidine (TMP, 0.25 g, 1.78 mmol) was dissolved in dry THF (10 ml) in a flask with a magnetic stirrer bar. The flask was flushed with argon and kept under an inert atmosphere. The mixture was cooled to −78° C., and n-BuLi (1.1 ml, 1.6M, 1.78 mmol) was added dropwise during 1 minute. The mixture was stirred for 5 minutes at this temperature, before adding a solution of 1-(4-chloro-phenyl)-1H-pyrazole (0.21 g, 1.1 mmol) in dry THF (2 ml). The solution was added dropwise over 2 minutes, and the obtained solution was stirred at this temperature for 20 minutes, before adding Bu3SnCl (0.36 g, 1.1 mmol) over 1 minute. The solution was allowed to slowly warm to RT and was then quenched with MeOH (1 ml). The residual mixture was partitioned between EtOAc and water, and the organic phase was dried and concentrated. Purification on silica afforded 0.2 g (40%) of an oil.

1. customThe flask was flushed with argon
2. additionThe solution was added dropwise over 2 minutes
3. stirringthe obtained solution was stirred at this temperature for 20 minutes
4. temperatureto slowly warm to RT
5. customwas then quenched with MeOH (1 ml)
6. customThe residual mixture was partitioned between EtOAc and water
7. customthe organic phase was dried
8. concentrationconcentrated
9. customPurification on silica

ORD record

ord-59ef79418a5f400e8e3f446ac1fc5315

Source dataset

uspto-grants-2011_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07998984B2