4-Methylmorpholine → tert-butyl 4-[[(Z)-[amino-[5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazin-2-yl]methylidene]amino]carbamoyl]piperidine-1-carboxylate

Participants

Reaction Steps

O-(7-Azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (74.3 g, 195.44 mmol) was added to a solution of N-Boc-isonipecotic acid (41.1 g, 179.15 mmol) and 4-methylmorpholine (35.9 mL, 325.74 mmol) in DMA (800 mL). The mixture was stirred for 10 minutes then (Z)-5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazine-2-carbohydrazonamide (45 g, 162.87 mmol) was added to the solution in one portion (exotherm observed from 22° C. to 27° C.). After a few minutes the product crystallised from the reaction mixture. The reaction mixture was removed from the vessel and filtered through a sinter. Additional DMA was added to wash product from the sides of the vessel (150 mL) and this was poured onto the filter cake. Isopropanol (600 mL) was added to the vessel and the remainder of the product in the vessel was suspended in this solvent using vigorous agitation. The isopropanol suspension was used to wash the filter cake once the DMA had been removed by suction. The filter cake was sucked dry then washed with MTBE and sucked dry once again. The filter cake was dried in vacuo to afford (Z)-tert-butyl 4-(2-(amino(5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)methylene)hydrazinecarbonyl)piperidine-1-carboxylate (76 g, 95%) as a yellow solid: 1H NMR Spectrum: (DMSO-d6) 1.40 (9H, s), 1.46 (9H, s), 1.63-1.9 (2H, m), 2.33-2.6 (2H, m, obscured by DMSO signal), 2.63-3.03 (2H, m), 3.18-3.48 (4H, m, obscured by water signal), 3.88-4.11 (2H, m), 6.43 (2H, s), 7.76 (2H, br), 8.84 (0.5H, s), 8.87 (0.5H, s), 9.85 (1H, s); Mass Spectrum [M+H]+=488

Provenance & Evidence