89937-26-8

General procedure: 3,6-dichloropyridazine (1 eq.), 4-hydroxypiperidine (1 eq.) and a nonprotonic base (e.g., Et3N or K2CO3, 2-3 eq.) are dissolved in DMSO or EtOH in a sealed vessel, and the reaction is heated until the feedstocks are shown to be completely consumed by TLC or HPLC monitoring. Upon completion of the reaction, post-treatment is carried out: the reaction mixture is partially evaporated, followed by the addition of water and filtration to collect the precipitated solid product (for cases such as 37); alternatively, the partially evaporated reaction mixture is partitioned between EtOAc and water, and the aqueous layer is extracted with EtOAc several times to ensure complete extraction. The organic layers are combined, dried over anhydrous Na2SO4 and concentrated under reduced pressure to give the crude product, which is finally purified by column chromatography.

[1] Bioorganic and Medicinal Chemistry, 2016, vol. 24, # 8, p. 1819 - 1839
[2] Patent: WO2016/54388, 2016, A1. Location in patent: Page/Page column 57
[3] Journal of Medicinal Chemistry, 1984, vol. 27, # 8, p. 1077 - 1083
[4] Bioorganic and Medicinal Chemistry Letters, 2011, vol. 21, # 24, p. 7281 - 7286
[5] Patent: WO2008/46226, 2008, A1. Location in patent: Page/Page column 42