Imidazole → Triphenylphosphine Oxide

Solid 1d (82 mg, 0.31 mmol), triphenylphosphine (274 mg, 1.03 mmol), and imidazole (140 mg, 2.05 mmol) are blended under argon by magnetic stirring before being dissolved in 1-methyl-2-pyrrolidinone (M-PYROL) (1.5 ml) at room temperature. Beads (1-3 mm) of iodine (261 mg, 1.03 mmol) are added over 5 min with slight heating observed. Further additions of triphenylphosphine, imidazole, and iodine (same quantities as above) are made in the order listed after 5 h, 24 h, and 56 h. More M-PYROL (0.5 ml) is added prior to the last addition. After 124 h, the reaction solution is partitioned between ethyl acetate (40 ml) and 10% sodium thiosulfate (15 ml). The aqueous layer is extracted with more ethyl acetate (3×15 ml). The combined organic layers are washed once with brine (15 ml), dried (MgSO4), and evaporated to a solid. A crop of triphenylphosphine oxide (Ph3PO) is obtained from a chilled ethyl acetate solution of this residue. More Ph3PO is removed by repeating this process with chloroform. Crude 1e is purified by preparative TLC (Analtech GF, 20×20 cm, 2,000 μ) using 9:1 CHCl3/MeOH as developing solvent. Pure 1e crystallized from 2-propanol as a white solid.

1. temperaturewith slight heating
2. custom56 h
3. additionto the last addition
4. waitAfter 124 h
5. customthe reaction solution is partitioned between ethyl acetate (40 ml) and 10% sodium thiosulfate (15 ml)
6. extractionThe aqueous layer is extracted with more ethyl acetate (3×15 ml)
7. washThe combined organic layers are washed once with brine (15 ml)
8. dry with materialdried (MgSO4)
9. customevaporated to a solid

ORD record

ord-724d7a1028724f48bd9aec2e2e6ff30b

Source dataset

uspto-grants-2009_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07488598B2