To a stirred solution of methyl-3-amino-5-phenylthiophene-carboxylate (233 mg, 1.0 mmol) and 1-methyl-4-trimethylsilanyloxy-1,2,3,6-tetrahydro-pyridine (370 mg, 2.0 mmol) in dichloroethane (3.0 mL) was added AcOH (0.114 mL, 2.0 eq) and followed addition of NaBH(OAc)3 (424 mg, 2.0 mmol) in one portion. The resultant reaction mixture was stirred at RT for weekend, aq. 10% NaOH (until basic) was added, after 30 min, reaction mixture was extracted with dichloromethane. The organic extract was washed with brine and dried. The crude product was purified on silica gel column using 20% EtOAc/hexane for unreacted starting material followed by CHCl3/MeOH/Et3N (180/16/1) furnished the 3-(1-methyl-piperidin-4-ylamino)-5-phenyl-thiophene-2-carboxylic acid methyl ester (240 mg, 73%). NMR 1H (CDCl3, 400 MHz): 7.64-7.6 (m, 2H), 7.43-7.34 (m, 3H), 6.83 (brs, 2H), 3.83 (s, 3H), 3.46-3.4 (m, 1H), 2.82-2.74 (m, 1H), 2.3 (s, 3H), 2.26-2.2 (m, 4H), 1.72-1.62 (m, 2H).
