Phosphate → 2-amino-7-aminomethyl-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid tert-butyl ester

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Reaction Steps

The above 2-amino-7-((2,2,2-trichloro-ethoxycarbonylamino)methyl)-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid tert-butyl ester (4.0 g, 8.0 mmol) was dissolved in a mixture of tetrahydrofuran (15 ml) and a aqueous phosphate buffer (pH 3; 5 ml) followed by addition of zinc (16 g, 0.244 mol). The reaction mixture was stirred for 6 h at room temperature at which time the solvent was removed in vacuo. To the residue was added diethyl ether (20 ml) and water (40 ml). Sodium carbonate was added to the aqueous phase until pH=8 and the aqueous phase was extracted with dichloromethane (3×). The combined organic phases were, dried (MgSO4), filtered and the solvent removed in vacuo. The residue was purified by flash chromatography on silica gel (90 g) using a mixture of dichloromethane/ethanol/25% ammonia in water 100:10:0.7 as eluant. Pure fractions were collected and the solvent evaporated in vacuo affording 1.52 g (61%) of 2-amino-7-aminomethyl-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid tert-butyl ester.

Provenance & Evidence