[C:1]([O:5][C:6]([C:8]1[C:16]2[CH2:15][CH:14]([CH2:17][N:18]3C(=O)C4C(=CC=CC=4)C3=O)[O:13][CH2:12][C:11]=2[S:10][C:9]=1[NH2:29])=[O:7])([CH3:4])([CH3:3])[CH3:2].NN>C(O)C.ClCCl>[C:1]([O:5][C:6]([C:8]1[C:16]2[CH2:15][CH:14]([CH2:17][NH2:18])[O:13][CH2:12][C:11]=2[S:10][C:9]=1[NH2:29])=[O:7])([CH3:4])([CH3:2])[CH3:3]In a 50-ml round-bottom flask, a suspension of 2-amino-5-(1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid tert-butyl ester (2.00 g, 4.8 mmol) in absolute ethanol (20 ml) was flushed with nitrogen and sealed with a rubber septum. Hydrazine (0.5 ml, 15.9 mmol) was added, followed by an additional portion of absolute ethanol (20 ml) at room temperature. The reaction mixture was heated to 80° C. for 3.5 hours and then allowed to stir at room temperature for 14 hours. The precipitate was filtered off and washed with absolute ethanol. The filtrate was concentrated in vacuo leaving an oil, which was dissolved in dichloromethane (30 ml) and refiltered. The solvent was evaporated in vacuo affording 1.2 g (86%) of 2-amino-5-aminomethyl-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid tert-butyl ester as a solid.
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