Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester → (3-Bromophenyl)acetaldehyde

Temperature

-78 °C

60 g (246 mmol) of ethyl(3-bromophenyl)acetate (Compound B1) was converted into the title compound (oil) using 255 ml (255 mmol) of diisobutyl aluminum hydride (DIBAL-H, 1M in hexane), 85.8 g (250 mmol) of (carbethoxy methylene)triphenylphosphorane and 1.7 g of 10% Pd/C. The procedure was as follows: To a cold solution (-78° C.) of Compound B1 in CH2Cl2 was added dropwise (over a span of 1 hour) the diisobutyl aluminum hydride (DIBAL-H, 1M solution in hexane). After the DIBAL-H addition was complete, the reaction was stirred at -78 ° C. for an additional hour. The reaction was quenched by the dropwise addition of methanol, followed by water and 10% HCl. The mixture was then warmed to 0° C., stirred for 10 minutes and then washed with water, 10% aqueous NaHCO3 and brine. The organic phase was dried over MgSO4 and the solvent distilled off at ambient temperature to give crude (3-bromophenyl)acetaldehyde. To a cold solution (0° C.) of this crude aldehyde in CH2Cl2 was added a solution of the (carbethoxy methylene)triphenylphosphorane reagent in CH2Cl2. The mixture was stirred for 16 hours, concentrated in vacuo and purified by flash chromatography (silica, 10% EtOAc-hexane) to give ethyl 4-(3-bromophenyl)but-2-enoate as a mixture of E:Z isomers. This isomeric mixture was dissolved in EtOAc and hydrogenated over 10% Pd/C for 6 hours. The catalyst was filtered off and the filtrate concentrated in vacuo to give the title compound as a white solid.

1. customThe reaction was quenched by the dropwise addition of methanol
2. temperatureThe mixture was then warmed to 0° C.
3. stirringstirred for 10 minutes
4. washwashed with water, 10% aqueous NaHCO3 and brine
5. dry with materialThe organic phase was dried over MgSO4
6. distillationthe solvent distilled off at ambient temperature

ORD record

ord-aef55961b02241fb942b5cd8a8be226f

Source dataset

uspto-grants-2000_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06025388