Stannous chloride dihydrate → 1-(3,7-Diamino-phenothiazin-10-yl)-ethanone

Participants

Reaction Steps

A mixture of 1-(3,7-dinitro-phenothiazin-10-yl)-ethanone (2 g, 6.04 mmol), tin (II) chloride dihydrate (14.17 g, 62.8 mmol), and ethanol (50 cm3) was heated to reflux and stirred at this temperature for 5 hours. The mixture was then cooled to room temperature and poured over ice water. The pH was adjusted to 7 with 5% sodium hydrogen carbonate before the product was extracted with ethyl acetate (3×50 cm3). The extracts were washed with brine and dried over magnesium sulphate, filtered, and concentrated to give the title compound (1.64 g, 100%) as a purple blue solid; vmax(KBr)/cm−1: 3445 (NH), 3424 (NH), 3368 (NH), 3322 (NH), 3203 (NH), 3054 (CH), 2995 (CH), 1706 (C═O), 1650 (NO2), 1590 (NO2); δH (250 MHz; CDCl3): 2.01 (3H, s, CH3), 5.09-5.43 (4H, brd s, NH), 6.47-6.51 (2H, dd, J 1.5, 8.25, ArH), 6.61 (2H, s, ArH), 7.11-7.15 (2H, d, J 8, ArH); δC (62.9 MHz; CDCl3): 169.1 (C═O), 147.2 (ArC), 128.1 (ArC), 127.6 (ArC), 127.3 (ArC), 112.3 (ArC), 111.5 (ArC), 22.6 (CH3); m/z (ES) 293.9 (95%, [M+H, Na]+), 272.0 (20%, [M+H]+), 227.9 (100%, [M+H, —Ac]+).

Provenance & Evidence