Sodium triacetoxyborohydride → 7-Bromo-2,9-dimethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole

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Reaktionsschritte

7-Bromo-9-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole (1.24 g, 4.68 mmol) was dissolved in a mixture of MeOH (20 mL) and CH2Cl2 (5 mL) and formaldehyde (0.56 mL, 37% aqueous solution) was added. After stirring for 1 h, NaBH(OAc)3 (1.98 g, 9.34 mmol) was added and the mixture stirred for a further 10 minutes. The mixture was diluted with methylene chloride (50 mL), washed with saturated Na2CO3 solution, concentrated and purified by flash column chromatography (40 g ISCO column eluting with methylene chloride and a methanol/ammonia mixture (10:1); gradient 100% methylene chloride to 90% methylene chloride over 30 min at 40 mL/min) to provide the title compound (1.15 g, 88%) as a white powder: 1H NMR (500 MHz, CDCl3) δ 7.40 (d, J=1.6 Hz, 1H), 7.32 (d, J=8.4 Hz, 1H), 7.16 (dd, J=8.3, 1.7 Hz, 1H), 3.61 (s, 2H), 3.55 (s, 3H), 2.86-2.76 (m, 4H), 2.56 (s, 3H).

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