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| Typical applications of Bredereck's reagent（CAS:5815-08-7）（13） |
| 2022-06-20 |
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2,5,6,7-tetrahydro-4H-indazol-4-one (CAS: 912259-10-0)
To 1,3-cyclohexane dione (22.4 g, 0.19 mol), add tert-butoxybis(dimethylamino)methane[CAS:5815-08-7, Bredereck’s Reagent] (23.1 g, 0.19 mol).
Stir the reaction at room temperature for 5 minutes. Add hydrazine dihydrochloride (20.55 g, 0.19 mol) to the reaction and stir at room temperature for 1 hour.
Add formic acid (50 mL) to the mixture. Bring the reaction to 100° C. and stirred for 2 hours. Cool the reaction and extract with 3:1 chloroform:IPA (10*60 mL each).
Combine the organics and dry over sodium sulfate. After filtration and concentration,
load the residue on silica gel column and flash with ethyl acetate to afford 21.6 g (82%) of the desired product as white-grey solid.
NMR matches the structure. MS (m/z): 137 [M+H]+.
Ref：US2009/111800, 2009, A1
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