Reaction #60349

Reaction equation

(6-Bromo-chroman-4-yl)-carbamic acid tert-butyl ester

n-Butyllithium

DMF

→

title compound

(6-formyl-chroman-4-yl)-carbamic acid tert-butyl ester

Solvents

THF

Conditions

Workup

1. 1
   workup.ADDITIONwas added drop-wise to the stirred solution
2. 2
   Temperaturethe system was slowly warmed to RT overnight
3. 3
   OtherThe reaction was quenched with saturated aqueous NH4Cl solution
4. 4
   Extractionextracted with EtOAc
5. 5
   DryingThe combined organics were dried with MgSO4
6. 6
   Concentrationconcentrated in vacuo
7. 7
   Otherto afford the crude compound, which
8. 8
   Otherwas purified by flash column chromatography

Procedure

(6-Bromo-chroman-4-yl)-carbamic acid tert-butyl ester (Step D) (3.859 g, 11.76 mmol) was dissolved in THF (50 mL) and cooled to −78° C. n-Butyllithium (2.5 M) (11.76 mL, 29.40 mmol) was added drop-wise to the stirred solution. The reaction mixture was stirred at −78° C. for 30 min and DMF (4.55 mL, 58.8 mmol) was added drop-wise and the system was slowly warmed to RT overnight. The reaction was quenched with saturated aqueous NH4Cl solution and extracted with EtOAc. The combined organics were dried with MgSO4 and concentrated in vacuo to afford the crude compound, which was purified by flash column chromatography to furnish the pure title compound.

Source