Sulfuric Acid → 5-Diethylphosphono-2-thiophenecarboxaldehyde
Reaction equation
[CH2:1]([O:3][P:4]([C:9]1[S:10][C:11]([CH:14]2N(C)CCN2C)=[CH:12][CH:13]=1)(=[O:8])[O:5][CH2:6][CH3:7])[CH3:2].S(=O)(=O)(O)[OH:22]>O>[CH2:6]([O:5][P:4]([C:9]1[S:10][C:11]([CH:14]=[O:22])=[CH:12][CH:13]=1)(=[O:8])[O:3][CH2:1][CH3:2])[CH3:7]Participants
4
Procedure
To a solution of [5-(1,3-dimethyl-imidazolidin-2-yl)-thiophen-2-yl]-phosphonic acid diethyl ester (17.2 g, 60.17 mmol) in water (20 ml) was added sulfuric acid (3 ml) over 5 mins. The reaction was stirred at r.t. for 20 min, diluted with water, extracted with EtOAc. The organic layer was washed with sat. NaHCO3, dried over MgSO4, filtrated, concentrated, purified by Biotage (80% EtOAc) to give (5-formyl-thiophen-2-yl)-phosphonic acid diethyl ester (7.2 g, 48.3%). 1H NMR (300 MHz, DMSO-d6): δ 10.02 (d, J=2.4 Hz, 1H), 8.09 (m, 1H), 7.75 (m, 1H), 4.05 (m, 4H), 1.24 (m, 6H). LC-MS m/z=249.4 [C9H13O4PS+H]+.