Hydrochloric Acid → Methyl 3,4-dihydro-2H-1,4-benzoxazine-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

Boron trifluoride diethyl etherate (7.10 mmol) is added dropwise to a mixture of 3-oxo-3,4-dihydro-2H-benzo[1,4]oxazine-5-carboxylic acid methyl ester (3.38 mmol) in THF (10 mL) to keep the temperature below 5° C. After 20 min NaBH4 (7.10 mmol) is added and the mixture is stirred at 5° C. for 90 min. EtOAc (6.0 mL) and hydrochloric acid (1.0 M, 6.0 mL) are added dropwise. The mixture is made basic by addition of aq. Na2CO3 solution, the layers are separated and the aq. layer is extracted with EtOAc. The combined organic layers are dried over MgSO4 and concentrated in vacuo to give a crude product which is purified by flash chromatography (gradient: heptane to heptane/EtOAc 3/7). LC-MS: tR=0.90 min; [M+CH3CN+H]+=235.3.

Provenance & Evidence