Triphenylphosphine → Triphenylphosphine Oxide

Participants

Reaction Steps

To a stirred solution of N-tert-butoxycarbonyl-L-prolinol (0.81 g, 4 mmol) 18 in dry DCM (10 mL) was added triphenylphosphine (5.24 g, 20 mmol) followed by 4(3H)-pyrimidone (0.77 g, 8 mmol). The solution was cooled in an ice bath and DIAD (3.24 g, 16 mmol) added dropwise over 10 min. After 48 h GC-MS indicated complete conversion of 18 and the reaction mixture was poured onto water (30 mL), the organic fraction collected and the aqueous phase washed with further DCM (2×20 mL). The combined organic fractions were washed with 1M NaOH (2×15 mL) then brine (1×15 mL) and dried over Na2SO4. Removal of bulk solvent yielded an orange gum, addition of hexanes/diethyl ether (1:1) resulted in formation of a precipitate of triphenylphosphine oxide, which was removed by filtration. Chromatography (ethyl acetate) afforded the desired product as a colorless oil (0.77 g, 69%). HRMS (ESI)=280.1655 (M+H)+. Calcd. for C14H22N3O3 280.1656. 1H NMR (600 MHz, CDCl3) δ 8.71 (s, 1H), 8.39 (d, J=6 Hz, 1H), 6.69 (d, J=6 Hz, 1H), 4.45-3.91 (m, 3H), 3.40-3.33 (m, 2H), 2.00-1.82 (m, 4H), 1.42 (s, 9H). TLC (UV254) Rf=0.49 (ethyl acetate).

Provenance & Evidence