tert-butyl (3R,4R)-1-(3-aminopyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-ylcarbamate → tert-butyl (3R,4R)-1-(3-(3-amino-6-(2,6-difluorophenyl)picolinamido)pyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-ylcarbamate

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3-amino-6-(2,6-difluorophenyl)picolinic acid and tert-butyl (3R,4R)-1-(3-aminopyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-ylcarbamate were coupled following method 11 (example 249), to yield tert-butyl (3R,4R)-1-(3-(3-amino-6-(2,6-difluorophenyl)picolinamido)pyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-ylcarbamate after HPLC purification. Alternatively, tert-butyl (3R,4R)-1-(3-(3-amino-6-(2,6-difluorophenyl)picolinamido)pyridin-4-yl)-4-(tert-butyldimethylsilyloxy)-piperidin-3-ylcarbamate could be obtained starting with tert-butyl (3R,4R)-1-(3-(3-amino-6-bromo-picolinamido)pyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-yl-carbamate and 2,6 difluorophenylboronic acid following the Suzuki procedure outlined in method 14. The TBDMS deprotection of tert-butyl (3R,4R)-1-(3-(3-amino-6-(2,6-difluorophenyl)picolinamido)pyridin-4-yl)-4-(tert-butyldimethylsilyloxy)piperidin-3-yl-carbamate was performed with 6N HCl, THF, methanol (1:2:1) at room temperature for 2 h. After volatile materials were removed, the crude material was stirred in 30% TFA in dichloromethane for 2 hours. After volatile materials were removed in vacuo, purification and lyophilization yielded 3-amino-N-(4-((3R,4R)-3-amino-4-hydroxy-piperidin-1-yl)pyridin-3-yl)-6-(2,6-difluorophenyl)picolinamide. HPLC. LCMS (m/z): 441.2 (MH+); LC Rt=2.03 min.

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