5FBO:
reference: Discovery of 8-Amino-imidazo[1,5-a]pyrazines as Reversible BTK Inhibitors for the Treatment of Rheumatoid Arthritis., Liu J, Guiadeen D, Krikorian A, Gao X, Wang J, Boga SB, Alhassan AB, Yu Y, Vaccaro H, Liu S, Yang C, Wu H, Cooper A, de Man J, Kaptein A, Maloney K, Hornak V, Gao YD, Fischmann TO, Raaijmakers H, Vu-Pham D, Presland J, Mansueto M, Xu Z, Leccese E, Zhang-Hoover J, Knemeyer I, Garlisi CG, Bays N, Stivers P, Brandish PE, Hicks A, Kim R, Kozlowski JA, ACS Med Chem Lett. 2015 Dec 19;7(2):198-203. doi: 10.1021/acsmedchemlett.5b00463., eCollection 2016 Feb 11. PMID: 26985298

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