1,8-Diazabicyclo(5.4.0)undec-7-ene → Methyl benzothieno[3,2-c]pyridine-3-carboxylate

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Reaction Steps

1-Benzothiophene-2,3-dicarbaldehyde (C180) (1.91 g, 10.0 mmol) is dissolved in CH2Cl2 (100 ml) and chilled in an ice bath. Methyl (acetylamino)(dimethoxyphosphoryl)acetate (C152) (2.63 g, 11.0 mmol) is dissolved in CH2Cl2 (50 ml) and added to 1,8-diazabicyclo[5.4.0]undec-7-ene (1.65 ml, 11.0 mmol), stirring for 5 minutes. This solution is added dropwise to the chilled thiophene solution. The reaction mixture is stirred in the ice bath for 1 h and then over night at rt. The reaction is concentrated in vacuo and the crude material is chromatographed over 500 g slurry-packed silica eluting with 50% ethyl acetate/hexane to afford methyl benzothieno[3,2-c]pyridine-3-carboxylate (C 181) as a white solid (73% yield). MS for C13H9NO2S, (EI) m/z: 243 (M)+.

Provenance & Evidence