Potassium Phosphate, Tribasic → HCID 9820147, compound

Participants

Reaction Conditions

Reaction Steps

To a nitrogen purged flask was charged palladium acetate (13.2 g, 59 mmoles, 0.04 eq), racemic BINAP (36.6 g, 59 mmoles, 0.04 eq), followed by 1.9 L toluene. The heterogeneous slurry was heated to 50° C. under nitrogen for 2 hours, cooled to 30° C., then the pyridyl chloride 41 (386.4 g, 1.45 moles, 1.0 eq) and Boc-2,6-difluoroaniline 42 (386.4 g, 1.69 moles, 1.2 eq), and K3PO4 (872 g, 4.1 moles, 2.8 eq) were added all at once followed by a 1.9 L toluene rinse. The heterogeneous reaction mixture was heated to 100° C. overnight and monitored by HPLC. When the reaction showed complete conversion to 43 by HPLC [Tret 41=17 min, Tret 43=20.5 min, Tret 44=17.6 min, monitored at 229 nm] (usually between 18-20 hours) the reaction was cooled to room temperature and the contents diluted with 1.94 L EtOAc. To this was added 1×1.94 L of 6N HCl, and both layers were filtered through celite. The celite wet cake was rinsed with 2×1.9 L EtOAc. The layers were separated and the organic layer washed with 1×1.9 L of brine, dried (MgSO4), filtered and concentrated to a brown, viscous oil. To remove the Boc-protecting group, the oil was dissolved in 1.94 L of methylene chloride and 388 mL TFA was added. The reaction was stirred overnight to facilitate Boc removal. The volatiles were removed in vacuo, EtOAc (1.9 L) and sufficient quantity of 1 or 6 N NaOH was added until the pH was 2-7. Then a sufficient quantity of 5% NaHCO3 was added to bring the pH to 8-9. The organic layer was separated and washed with 1×5% NaHCO3, dried (MgSO4), filtered an concentrated to a brown oil/liquid. The crude oil/liquid was azeodried twice with a sufficient quantity of toluene. At times the free base precipitated out resulting in a slurry. The residue was dissolved in 500 mL toluene and 1.6 L 1N HCl/ether solution was added, which resulted in the solids crashing out. Heat was applied until the homogenized/solids broke up. If necessary, 200 mL of EtOAc can be added to facilitate the break up. After cooling, the solid 44 was isolated by vacuum filtration.

Provenance & Evidence