REDUCTION OF WEINREB AMIDE TO ALDEHYDE
Using LAH
F SM/Reagent |
F Eq |
F Apparatus |
Weinreb Amide (FW: 187.28) |
1.0 |
Multi Neck Flask |
LAH (1M in Et2O) |
1.5 |
Stirrer |
Et2O (Anhy) |
3ml/1mmol SM |
Cold bath |
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Procedure
1. Dissolve Weinreb Amide in Et2O. Stir. Cool to 0 oC
2. Add LAH/Et2O [1]
3. Stir the mixture at 0 oC for 1 hr [2]
4. Quench slowly w/sat aq. KHSO4 [3]
5. Warm to R.T. Stir for 30 min
6. Add 1N HCl and stir for 2 hrs [4] ® separate
7. Wash organic layer w/sat NaHCO3 then water and brine
8. Dry w/MgSO4. Filter
9. Concentrate in vacuo [5]® crude as colorless liquid
10. NMR w/CDCl3. Yield >95% [6]
Notes:
[1] Inside temp: < 0 oC during addition. ¯ white appear
[2] Follow reaction by TLC w/10% EtOAc/Hex (I2 or KMnO4)
[5] Rotovac bath temperature: 40 oC
[6] No further purification
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