Sodium Azide → 3-(1H-Tetrazol-5-yl)-1,4,5,6-tetrahydrocyclopenta[c]pyrazole

HRID 475498Notes

Reaction equation

[NH:1]1[C:5]2[CH2:6][CH2:7][CH2:8][C:4]=2[C:3]([C:9]#[N:10])=[N:2]1.[N-:11]=[N+:12]=[N-:13].[Na+]>CN(C=O)C>[N:10]1[NH:11][N:12]=[N:13][C:9]=1[C:3]1[C:4]2[CH2:8][CH2:7][CH2:6][C:5]=2[NH:1][N:2]=1

Participants

Conditions

Temperature: 175 °C

Procedure

1,4,5,6-Tetrahydro-cyclopentapyrazole-3-carbonitrile (0.022 g, 0.165 mmol) and sodium azide (0.086 g, 1.30 mmol) were taken up in DMF (3 cm3) at heated under microwave irradiation to 175° C. for 20 minutes. The solution was cooled to room temperature, filtered and the filtered solid washed with ethyl acetate. The combined solutions was added to saturated aqueous sodium bicarbonate (20 cm3) and washed with ethyl acetate. The aqueous layer was acidified to pH 1 with the addition of 1M aqueous hydrochloric acid and extracted into ethyl acetate. The ethyl acetate washes were combined and solvent removed under reduced pressure, the resulting solid purified by preparative HPLC to give 3-(2H-tetrazol-5-yl)-1,4,5,6-tetrahydro-cyclopentapyrazole as a white solid (0.012 g, 0.068 mmol, 41%). 1H NMR δ (CD3OD): 2.88 (t-like, 2H, J=7.0), 2.82 (t-like, 2H, J=7.3), 2.64 (quintet-like, 2H, J=7.1); m/z (ES+): 177 [M+H]+.

Workup

temperatureThe solution was cooled to room temperature
filtrationfiltered
washthe filtered solid washed with ethyl acetate
additionThe combined solutions was added to saturated aqueous sodium bicarbonate (20 cm3)
washwashed with ethyl acetate
additionThe aqueous layer was acidified to pH 1 with the addition of 1M aqueous hydrochloric acid
extractionextracted into ethyl acetate
customsolvent removed under reduced pressure
customthe resulting solid purified by preparative HPLC

Sources & evidence

ORD record: ord-7cd5f76d566440a5a9c26a9e34d7846e
Source dataset: uspto-grants-2014_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08637555B2

Reaction notes

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