Ethanol → (+/-)-9-Bromo-9,10-dihydropyrrolo[2,1-b][1,3]benzothiazepine

Participants

Reaction Steps

To a solution of 24a (0.26 g, 1.0 mmol) in anhydrous ethyl ether (4 ml) was added dropwise a solution of PBr3 (0.13 g, 0.5 mmol) in anhydrous ethyl ether (1 ml) and the reaction mixture was kept at reflux temperature for 2 hours under nitrogen. Anhydrous ethanol was added (0.2 ml) and the resulting solution was heated to reflux temperature for another hour. Five ml of an aqueous solution of 5% Na2CO3 were then added, the organic phase was separated, anhydrified and evaporated. The crude product was chromatographed (hexane and chloroform 1:1) to give 25a (0.2 g, 64% yield) as colourless prisms: melting point 115-116° C. (cyclohexane); 1H NMR (CDCl3) δ7.46-7.09 (m, 4H); 6.93 (m, 1H), 6.39 (m, 1H), 6.12 (m, 1H), 5.75 (dd, 1H, J=6.9, 2.6 Hz), 5.07 (dd, 1H, J=14.7, 2.6 Hz), 4.61 (dd, 1H, J=14.7, 6.9 Hz). Anal. (C12H10BrNOS): C, H, N.

Provenance & Evidence