[CH3:1][C:2]1([C:12]([NH2:14])=O)[S:9](=[O:11])(=[O:10])[C:5]2[S:6][CH:7]=[CH:8][C:4]=2[CH2:3]1>C1COCC1>[NH2:14][CH2:12][C:2]1([CH3:1])[S:9](=[O:11])(=[O:10])[C:5]2[S:6][CH:7]=[CH:8][C:4]=2[CH2:3]1Borane-dimethylsulfide complex (11.12 mL, 10M) was added to a stirred solution of 2,3-dihydro-2-methylthieno[2,3-b]thiophene-2-carboxamide-1,1-dioxide (2.57 g, 11.12 mmol) in THF (75 mL) at room temperature. The reaction mixture was refluxed under a nitrogen atmosphere for 1.5 h and then cooled in an ice bath to 10° C. and slowly quenched with 6N HCl. After gas evolution ceased, the acidic solution was refluxed for 2 h. The reaction mixture was cooled to room temperature and extracted twice with ether. The aqueous phase was made alkaline with aqueous NaOH and extracted with ethyl acetate (5×300 mL). The combined ethyl acetate extracts were washed with saturated brine and then dried over MgSO4. The solution was filtered and the solvent removed in vacuo to give 2-aminomethyl-2,3-dihydro-2-methylthieno[2,3-b]thiophene-1,1-dioxide as an oil (2.2 g, 91%). 1H NMR (300 MHz,DMSO-d6) 1.40(s,3H), 2.85-3.00(m,3H), 3.30(d,1H), 7.05(s,1H), 8.05(s,1H).
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