(2,2-difluoroacetyl) 2,2-difluoroacetate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyrazin-2-yl-hydrazine 23a (1 g, 9 mmol) was added in an eggplant-shaped bottle (25 mL), followed by dropwise addition of difluoroacetic anhydride (4 g, 22.98 mmol) at 0° C. After stirring at room temperature for 3 hours, the reaction mixture was concentrated under reduced pressure to obtain crude 2,2-difluoro-N′-pyrazin-2-yl-acetohydrazide difluoroacetate 23b (2 g) as a brown oil. The product was used directly in the next reaction without purification. the reaction mixture was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyrazin-2-yl-hydrazine 23a (1 g, 9 mmol) was added in an eggplant-shaped bottle (25 mL), followed by dropwise addition of difluoroacetic anhydride (4 g, 22.98 mmol) at 0° C. After stirring at room temperature for 3 hours, the reaction mixture was concentrated under reduced pressure to obtain crude 2,2-difluoro-N′-pyrazin-2-yl-acetohydrazide difluoroacetate 23b (2 g) as a brown oil. The product was used directly in the next reaction without purification. the reaction mixture was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-(2,2-difluoroethyl)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-7-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-2-amine TFA salt (10 mg, 0.018 mmol), 2,2-difluoroacetic anhydride (4.7 mg, 0.027 mmol), and DIPEA (7.0 mg, 0.054 mmol) in DCM (90 μL) was stirred at room temperature for 2 h. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (5 mg) as a white solid. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.21 (d, J=7.1 Hz, 1.2H), 1.29 (d, J=6.6 Hz, 1.8H), 1.92-2.03 (m, 2H), 2.09-2.19 (m, 2H), 2.58-2.69 (m, 1H), 2.98-3.07 (m, 2.4H), 3.11-3.17 (m, 0.6H), 3.35-3.44 (m, 2H), 3.78 (td, J=14.5, 4.3 Hz, 2H), 4.11 (d, J=17.2 Hz, 1H), 4.42-4.51 (m, 1H), 4.60-4.67 (m, 0.6H), 4.73-4.77 (m, 0.4H), 5.05 (d, J=17.7 Hz, 0.6H), 5.11-5.18 (m, 0.4H), 5.89-6.22 (m, 1H), 6.39-6.73 (m, 1H), 6.85-6.91 (m, 1H), 6.99 (ddd, J=11.4, 8.6, 3.0 Hz, 1H), 7.18 (td, J=9.3, 5.4 Hz, 1H); ESI-MS m/z [M+H]+ 517.9. The crude reaction mixture filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR) purified via HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-(2,2-difluoroethyl)-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), DIPEA (10.8 mg, 0.083 mmol), and 2,2-difluoroacetic anhydride (7.3 mg, 0.042 mmol) in DCM (278 μL) was stirred at room temperature for 2 h. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (3 mg) as a clear oil. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.92-2.02 (m, 2H), 2.09-2.17 (m, 2H), 2.80 (t, J=5.9 Hz, 0.8H), 2.86 (t, J=5.4 Hz, 1.2H), 2.96-3.04 (m, 2H), 3.34-3.43 (m, 2H), 3.77 (td, J=14.3, 4.0 Hz, 2H), 3.90 (t, J=5.8 Hz, 1.2H), 3.93 (t, J=6.1 Hz, 0.8H), 4.46 (tt, J=7.6, 3.7 Hz, 1H), 4.61 (s, 0.8H), 4.63 (s, 1.2H), 5.89-6.21 (m, 1H), 6.42-6.71 (m, 1H), 6.84-6.91 (m, 1H), 6.98 (ddd, J=11.2, 8.5, 3.0 Hz, 1H), 7.17 (td, J=9.2, 5.6 Hz, 1H); ESI-MS m/z [M+H]+ 504.4. The crude reaction mixture filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR) purified via HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-(2,2-difluoroethyl)-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), DIPEA (10.8 mg, 0.083 mmol), and 2,2-difluoroacetic anhydride (7.3 mg, 0.042 mmol) in DCM (278 μL) was stirred at room temperature for 2 h. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (3 mg) as a clear oil. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.92-2.02 (m, 2H), 2.09-2.17 (m, 2H), 2.80 (t, J=5.9 Hz, 0.8H), 2.86 (t, J=5.4 Hz, 1.2H), 2.96-3.04 (m, 2H), 3.34-3.43 (m, 2H), 3.77 (td, J=14.3, 4.0 Hz, 2H), 3.90 (t, J=5.8 Hz, 1.2H), 3.93 (t, J=6.1 Hz, 0.8H), 4.46 (tt, J=7.6, 3.7 Hz, 1H), 4.61 (s, 0.8H), 4.63 (s, 1.2H), 5.89-6.21 (m, 1H), 6.42-6.71 (m, 1H), 6.84-6.91 (m, 1H), 6.98 (ddd, J=11.2, 8.5, 3.0 Hz, 1H), 7.17 (td, J=9.2, 5.6 Hz, 1H); ESI-MS m/z [M+H]+ 504.4. The crude reaction mixture filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR) purified via HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), 2,2-difluoroacetic anhydride (7.4 mg, 0.042 mmol), and DIPEA (10.94 mg, 0.085 mmol) in DCM (141 μL) was stirred at room temperature for 1 h. Purification by HPLC Method A gave the title compound as a TFA salt (8.2 mg) as an off-white film. 1H NMR (500 MHz, methanol-d4, mixture of rotamers) δ ppm 1.27 (dd, J=7.6, 6.6 Hz, 6H), 1.51 (d, J=6.8 Hz, 2.1H), 1.62 (d, J=6.8 Hz, 0.9H), 1.90-2.00 (m, 2H), 2.09-2.17 (m, 2H), 2.65-2.75 (m, 1H), 2.80-3.03 (m, 3H), 3.25 (td, J=12.9, 3.9 Hz, 0.3H), 3.34-3.42 (m, 2H), 3.52-3.61 (m, 0.7H), 4.11-4.21 (m, 1.7H), 4.46 (dt, J=7.3, 3.7 Hz, 1H), 4.66 (dd, J=13.4, 5.6 Hz, 0.3H), 4.91-4.98 (m, 0.3H), 5.25 (q, J=6.7 Hz, 0.7H), 6.44-6.69 (m, 1H), 6.84-6.92 (m, 1H), 6.99 (ddd, J=11.3, 8.4, 3.2 Hz, 1H), 7.18 (td, J=9.3, 5.4 Hz, 1H); ESI-MS m/z [M+H]+ 496.90. Purification by HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), 2,2-difluoroacetic anhydride (7.4 mg, 0.042 mmol), and DIPEA (10.94 mg, 0.085 mmol) in DCM (141 μL) was stirred at room temperature for 1 h. Purification by HPLC Method A gave the title compound as a TFA salt (8.2 mg) as an off-white film. 1H NMR (500 MHz, methanol-d4, mixture of rotamers) δ ppm 1.27 (dd, J=7.6, 6.6 Hz, 6H), 1.51 (d, J=6.8 Hz, 2.1H), 1.62 (d, J=6.8 Hz, 0.9H), 1.90-2.00 (m, 2H), 2.09-2.17 (m, 2H), 2.65-2.75 (m, 1H), 2.80-3.03 (m, 3H), 3.25 (td, J=12.9, 3.9 Hz, 0.3H), 3.34-3.42 (m, 2H), 3.52-3.61 (m, 0.7H), 4.11-4.21 (m, 1.7H), 4.46 (dt, J=7.3, 3.7 Hz, 1H), 4.66 (dd, J=13.4, 5.6 Hz, 0.3H), 4.91-4.98 (m, 0.3H), 5.25 (q, J=6.7 Hz, 0.7H), 6.44-6.69 (m, 1H), 6.84-6.92 (m, 1H), 6.99 (ddd, J=11.3, 8.4, 3.2 Hz, 1H), 7.18 (td, J=9.3, 5.4 Hz, 1H); ESI-MS m/z [M+H]+ 496.90. Purification by HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyrazin-2-yl-hydrazine 23a (1 g, 9 mmol) was added in an eggplant-shaped bottle (25 mL), followed by dropwise addition of difluoroacetic anhydride (4 g, 22.98 mmol) at 0° C. After stirring at room temperature for 3 hours, the reaction mixture was concentrated under reduced pressure to obtain crude 2,2-difluoro-N′-pyrazin-2-yl-acetohydrazide difluoroacetate 23b (2 g) as a brown oil. The product was used directly in the next reaction without purification. the reaction mixture was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-(2,2-difluoroethyl)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-7-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-2-amine TFA salt (10 mg, 0.018 mmol), 2,2-difluoroacetic anhydride (4.7 mg, 0.027 mmol), and DIPEA (7.0 mg, 0.054 mmol) in DCM (90 μL) was stirred at room temperature for 2 h. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (5 mg) as a white solid. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.21 (d, J=7.1 Hz, 1.2H), 1.29 (d, J=6.6 Hz, 1.8H), 1.92-2.03 (m, 2H), 2.09-2.19 (m, 2H), 2.58-2.69 (m, 1H), 2.98-3.07 (m, 2.4H), 3.11-3.17 (m, 0.6H), 3.35-3.44 (m, 2H), 3.78 (td, J=14.5, 4.3 Hz, 2H), 4.11 (d, J=17.2 Hz, 1H), 4.42-4.51 (m, 1H), 4.60-4.67 (m, 0.6H), 4.73-4.77 (m, 0.4H), 5.05 (d, J=17.7 Hz, 0.6H), 5.11-5.18 (m, 0.4H), 5.89-6.22 (m, 1H), 6.39-6.73 (m, 1H), 6.85-6.91 (m, 1H), 6.99 (ddd, J=11.4, 8.6, 3.0 Hz, 1H), 7.18 (td, J=9.3, 5.4 Hz, 1H); ESI-MS m/z [M+H]+ 517.9. The crude reaction mixture filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR) purified via HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of N-(2,2-difluoroethyl)-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), DIPEA (10.8 mg, 0.083 mmol), and 2,2-difluoroacetic anhydride (7.3 mg, 0.042 mmol) in DCM (278 μL) was stirred at room temperature for 2 h. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (3 mg) as a clear oil. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.92-2.02 (m, 2H), 2.09-2.17 (m, 2H), 2.80 (t, J=5.9 Hz, 0.8H), 2.86 (t, J=5.4 Hz, 1.2H), 2.96-3.04 (m, 2H), 3.34-3.43 (m, 2H), 3.77 (td, J=14.3, 4.0 Hz, 2H), 3.90 (t, J=5.8 Hz, 1.2H), 3.93 (t, J=6.1 Hz, 0.8H), 4.46 (tt, J=7.6, 3.7 Hz, 1H), 4.61 (s, 0.8H), 4.63 (s, 1.2H), 5.89-6.21 (m, 1H), 6.42-6.71 (m, 1H), 6.84-6.91 (m, 1H), 6.98 (ddd, J=11.2, 8.5, 3.0 Hz, 1H), 7.17 (td, J=9.2, 5.6 Hz, 1H); ESI-MS m/z [M+H]+ 504.4. The crude reaction mixture filtered through a hydrophilic PTFE 0.45 μm filter (Millipore® Millex-LCR) purified via HPLC Method A

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-3-amine TFA salt (15 mg, 0.028 mmol), 2,2-difluoroacetic anhydride (7.4 mg, 0.042 mmol), and DIPEA (10.94 mg, 0.085 mmol) in DCM (141 μL) was stirred at room temperature for 1 h. Purification by HPLC Method A gave the title compound as a TFA salt (8.2 mg) as an off-white film. 1H NMR (500 MHz, methanol-d4, mixture of rotamers) δ ppm 1.27 (dd, J=7.6, 6.6 Hz, 6H), 1.51 (d, J=6.8 Hz, 2.1H), 1.62 (d, J=6.8 Hz, 0.9H), 1.90-2.00 (m, 2H), 2.09-2.17 (m, 2H), 2.65-2.75 (m, 1H), 2.80-3.03 (m, 3H), 3.25 (td, J=12.9, 3.9 Hz, 0.3H), 3.34-3.42 (m, 2H), 3.52-3.61 (m, 0.7H), 4.11-4.21 (m, 1.7H), 4.46 (dt, J=7.3, 3.7 Hz, 1H), 4.66 (dd, J=13.4, 5.6 Hz, 0.3H), 4.91-4.98 (m, 0.3H), 5.25 (q, J=6.7 Hz, 0.7H), 6.44-6.69 (m, 1H), 6.84-6.92 (m, 1H), 6.99 (ddd, J=11.3, 8.4, 3.2 Hz, 1H), 7.18 (td, J=9.3, 5.4 Hz, 1H); ESI-MS m/z [M+H]+ 496.90. Purification by HPLC Method A