Toluene → tert-butyl 2,4-dimethoxybenzyl((S)-3-((R)-4-benzyl-2-oxooxazolidin-3-yl)-2-(4-chlorophenyl)-3-oxopropyl)carbamate

Temperature

-78 °C

(R)-4-benzyl-3-(2-(4-chlorophenyl)acetyl)oxazolidin-2-one (3.00 g, 9.10 mmol) was dissolved in DCM (91 mL) and cooled to −78° C. A 1M toluene solution of TiCl4 (11.4 mL, 11.4 mmol) was added to the solution followed by DIEA (1.66 mL, 9.55 mmol) to afford a dark purple reaction. This was allowed to stir for 15 minutes before the tert-butyl 2,4-dimethoxybenzyl(methoxymethyl)carbamate (3.40 g, 10.9 mmol) was added as a solution in DCM (10 mL) dropwise. The reaction was allowed to stir for 15 minutes at −78° C., then allowed to warm to −18° C. in a brine-ice bath for one hour. This reaction was allowed to warm slowly to 0° C. over a 2.5 hour period. The reaction was then quenched with the addition of saturated NH4Cl solution (100 mL). The layers were separated, and the organic layers was extracted once with DCM. The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo to afford a yellow oil. The residue was purified by chromatography (silica gel eluted with 4:1 hexanes:ethyl acetate) to afford the pure material as a colorless oil tert-butyl 2,4-dimethoxybenzyl((S)-3-((R)-4-benzyl-2-oxooxazolidin-3-yl)-2-(4-chlorophenyl)-3-oxopropyl)carbamate (4.07 g, 73.5% yield). This tert-butyl 2,4-dimethoxybenzyl((S)-3-((R)-4-benzyl-2-oxooxazolidin-3-yl)-2-(4-chlorophenyl)-3-oxopropyl)carbamate (680 mg, 1.12 mmol) was dissolved in DCM (10.6 mL) and water (560 uL; 19:1 DCM:water) at ambient temperature. The solution was treated with DDQ (380 mg, 1.67 mmol), and the reaction was allowed to stir for one day to afford reaction completion by TLC and LCMS analysis. The reaction was diluted with DCM and washed twice with half saturated NaHCO3 solution. The organic layer was dried over MgSO4, filtered, and concentrated in vacuo to afford a yellow-orange oil. The residue was purified by chromatography (silica gel eluted with 9:1 hexanes:ethyl acetate) to afford a mixture of the aldehyde by-product and tert-butyl (S)-3-((R)-4-benzyl-2-oxooxazolidin-3-yl)-2-(4-chlorophenyl)-3-oxopropylcarbamate (not separable) as a pale-yellow oil (729 mg combined mass). LC/MS (APCI+) m/z 359.1 [M−BOC+H]+.

1. customto afford
2. customa dark purple reaction
3. temperatureto warm to −18° C. in a brine-ice bath for one hour
4. temperatureto warm slowly to 0° C. over a 2.5 hour period
5. customThe reaction was then quenched with the addition of saturated NH4Cl solution (100 mL)
6. customThe layers were separated
7. extractionthe organic layers was extracted once with DCM
8. dry with materialThe combined organic layers were dried over MgSO4
9. filtrationfiltered
10. concentrationconcentrated in vacuo
11. customto afford a yellow oil
12. customThe residue was purified by chromatography (silica gel eluted with 4:1 hexanes:ethyl acetate)

ORD record

ord-b84d8c5c0f3e458996da2123534e086b

Source dataset

uspto-grants-2014_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08853199B2