Ammonium Chloride → tert-butyl 5-((diphenoxyphosphoryl)oxy)-2H-1,4-oxazine-4(3H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

Tert-butyl 3-oxomorpholine-4-carboxylate (5.2 g, 25.8 mmol) was dissolved in dry THF (52 ml). The mixture was cooled to −30° C. and (bis(trimethylsilyl)amino) lithium (1M THF solution, 28.4 ml, 28.4 mmol) was added dropwise. The resulting mixture was stirred for 1 hr, then diphenyl phosphorochloridate (7.3 g, 27.1 mmol) was added dropwise. The resulting mixture was allowed to warm slowly to ambient temperature over 6 hrs, after which time no starting material was present by HPLC. The reaction mixture was poured into saturated ammonium chloride solution (100 ml) and diluted with ethyl acetate (100 ml). The organic phase was separated and washed with sat NaHCO3 (50 ml), then brine (50 ml), dried (MgSO4), filtered and concentrated. The residue was purified on silica gel, eluting with 25-30% ethyl acetate/petrol. This gave the title compound as an oil which solidified on standing (7.59 g, 68%); 1H-NMR (CDCl3) 1.35 (9H, s), 3.54 (2H, dt), 3.87 (2H, m), 6.26 (1H, s), 7.11-7.17 (6H, m), 7.24-7.28 (4H, m); 31P-NMR (CDCl3)-16.07; 13C-NMR (CDCl3) 28.1, 42.0, 65.8, 120.0, 120.03, 120.09, 120.13, 125.19, 125.61, 125.62, 129.6, 129.86, 129.9; MS ES(+) 378.0 (M+-tBu).

Provenance & Evidence