5-Bromoisoquinoline

5-Bromoisoquinoline is a synthetic intermediate useful for pharmaceutical synthesis.

White to yellow-brown crystals

Starting material employed in palladium-catalyzed aminomethylation and amination reactions.

[1] W. Brown, A. Gouliaev. “Bromination of Isoquinoline, Quinoline, Quinazoline and Quinoxaline in Strong Acid.” ChemInform 98 1 (2002).

To mechanically stirred concd H2SO4 (42.5 mL) at 0 °C, isoquinoline (1; 5 mL, 42.5 mmol) was slowly added. The mixture was cooled to –25 °C, and NBS (9.83 g, 55.2 mmol) was added at such a rate that the reaction temperature was kept between –25 °C and –22 °C. The mixture was stirred at -22±1 °C for 2 h and at -18±1 °C for 3h. The mixture was then worked up as described above to give 6.16 g (72%) as a slightly off-white solid after chromatography; mp 81–82 °C. The solid was further purified by sublimation (75 °C/0.2 mmHg) to give 5-Bromoisoquinoline as a white powder[1].

[1] Patent: US2008/318941, 2008, A1. Location in patent: Page/Page column 22
[2] Patent: WO2009/23844, 2009, A2. Location in patent: Page/Page column 105-106
[3] Patent: US2008/200471, 2008, A1. Location in patent: Page/Page column 45; 45-46
[4] Patent: US2010/16297, 2010, A1. Location in patent: Page/Page column 25
[5] Patent: WO2010/21797, 2010, A1. Location in patent: Page/Page column 68