Reacción #561138

Ecuación de reacción

diisopropyl azodicarboxylate

Triphenylphosphine

5-bromo-2-nitrophenol

methyl(−)—(S)-lactate

→

(R)-methyl 2-(5-bromo-2-nitrophenoxy)propanoate

Rendimiento 94.0%

Disolventes

methylene chloride

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe orange solution was warmed to room temperature
2. 2
   workup.STIRRINGstirred for 12 h
3. 3
   Concentraciónconcentrated to ca. 1.0 mL
4. 4
   workup.ADDITIONdiluted with pentane (7 mL) and diethyl ether (8 mL)
5. 5
   Filtraciónfiltered
6. 6
   Lavadorinsed with diethyl ether-pentane (15 mL)
7. 7
   ConcentraciónThe filtrate was concentrated to dryness under reduced pressure
8. 8
   Otrothe residue was purified by flash column chromatography on silica gel (hexanes to ethyl acetate gradient)

Procedimiento

Triphenylphosphine (624.0 mg, 2.38 mmol) was added at room temperature to a solution of 5-bromo-2-nitrophenol A-15 (400.0 mg, 1.83 mmol) and methyl(−)—(S)-lactate (0.149 mL, 1.56 mmol) in anhydrous methylene chloride (18.3 mL) under an atmosphere of argon. After 10 mins of stirring, the reaction mixture was cooled to 0° C. and diisopropyl azodicarboxylate (0.360 mL, 1.83 mmol) was added dropwise. The orange solution was warmed to room temperature, stirred for 12 h, then concentrated to ca. 1.0 mL, diluted with pentane (7 mL) and diethyl ether (8 mL), filtered and rinsed with diethyl ether-pentane (15 mL). The filtrate was concentrated to dryness under reduced pressure, and the residue was purified by flash column chromatography on silica gel (hexanes to ethyl acetate gradient) to give (R)-methyl 2-(5-bromo-2-nitrophenoxy)propanoate (R)-A-16 as a yellow solid (525.0 mg; Yield=94%). MS (ESI) [M+1]+ 304, 306.

Fuente