Welcome to LookChem.com Sign In | Join Free

Details

Home > Chemical Encyclopedia > Chemical Technology > Organic Chemical Technology >
 Diels-Alder reaction: (1S-endo)-3-(Bicyclo[2.2.1]hept-5-en-2-ylcarbonyl)-2-oxazolidinone
  • Diels-Alder reaction: (1S-endo)-3-(Bicyclo[2.2.1]hept-5-en-2-ylcarbonyl)-2-oxazolidinone
  • (1S-endo)-3-(Bicyclo[2.2.1]hept-5-en-2-ylcarbonyl)-2-oxazolidinone (CAS no.: 109299-97-0) could be produced through the following synthetic routes.

    A. Bistriflamide of (1S,2S)-1,2-diphenylethylenediamine. A 50-mL, one-necked, round-bottomed flask, equipped with a magnetic stirring bar, is charged with 1.06 g (5 mmol) of (1S,2S)-1,2-diphenylethylenediamine (CAS no ), 2.1 mL (15 mmol) of triethylamine, 12.2 mg (0.1 mmol) of 4-dimethylaminopyridine (P) and 25 mL of methylene chloride. The mixture is stirred to dissolve the solids, cooled to -78°C with a solid carbon dioxide/acetone bath, and 3.39 g (12 mmol) of trifluoromethanesulfonic anhydride is added dropwise. The cooling bath is removed and the mixture is allowed to warm to ambient temperature over 30 min. The mixture is then poured into 4% aqueous sodium bicarbonate, the phases are separated, and the aqueous phase is washed with 15 mL of methylene chloride. The combined organic phases are washed with 1 N hydrochloric acid, with brine, and then dried over anhydrous sodium sulfate and filtered. The filtrate is concentrated under reduced pressure and the residue is subjected to flash chromatography4 on 100 g of silica gel (15% ethyl acetate-hexane, v/v) to give 1.64 g (69%) of the bistriflamide of (1S,2S)-1,2-diphenylethylenediamine as colorless crystals, mp 213–214°C .

    B. Acryloyl-2-oxazolidinone (CAS no ). A flame-dried, 1-L, one-necked, round-bottomed flask, equipped with a magnetic stirring bar, is charged with 8.71 g (100 mmol) of 2-oxazolidinone, flushed with argon, and then 500 mL of tetrahydrofuran is introduced. The mixture is stirred to dissolve solids, cooled to 0°C, and 33.3 mL (100 mmol) of 3 M methylmagnesium bromide in ether is slowly added. After the solution is stirred for 10 min at 0°C, 11.6 mL (115 mmol) of 3-bromopropionyl chloride is added dropwise. The cooling bath is removed and the mixture is allowed to warm to ambient temperature over 30 min. The mixture is diluted with 600 mL of peroxide-free ether and washed with saturated aqueous ammonium chloride. The organic phase is dried over magnesium sulfate and filtered. To the filtrate, stirred at ambient temperature, is added 69 mL (500 mmol) of triethylamine. A colorless precipitate forms immediately and the resulting slurry is stirred at ambient temperature for 3 hr, then poured into a 1:1 mixture of saturated aqueous ammonium chloride and 1 N aqueous hydrochloric acid. The aqueous layer is extracted with 200 mL of peroxide-free ether, and the combined organic phases are dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue is subjected to flash chromatography4 on 150 g of silica gel (35% ethyl acetate-hexane, v/v) to give 5.81 g (41%) of acryloyl-2-oxazolidinone as colorless crystals, mp 82–83°C.

    C. Diels-Alder reaction. All reagents and glassware are dried rigorously. A flame-dried, 250-mL, three-necked, round-bottomed flask, equipped with a magnetic stirring bar and a reflux condenser, is charged with 1.31 g (2.75 mmol) of bistriflamide of (1S,2S)-1,2-diphenylethylenediamine (dried at 80°C and 1 mm) and placed under dry argon. (20 mL) is added, the mixture is heated to 80°C with stirring to effect solution, cooled to ambient temperature, and treated dropwise with 1.37 mL (2.74 mmol) of 2 M trimethylaluminum in toluene. After the evolution of gases ceases, the homogeneous mixture is heated to 80°C (oil bath) for 3 hr. The heating bath is removed, the mixture is cooled to ambient temperature, the reflux condenser is replaced by a glass stopper, and the solvent is removed under reduced pressure (oil pump) that is maintained for an additional 30 min. The resulting solid is dissolved in 10 mL of dry methylene chloride and overlayered with 50 mL of dry heptane. Colorless crystals are deposited after 20 hr. The supernatant liquid is drawn off by syringe and the residual solid is dissolved in 50 mL of methylene chloride. The solution is cooled to -78°C and a solution of 7.76 g (55 mmol) of acryloyl-2-oxazolidinone in 50 mL of methylene chloride is introduced through a cannula. The mixture is stirred for 5 min at -78°C and then 5.7 mL (71 mmol) of neat, cold (-78°C) cyclopentadiene is slowly introduced through a cannula along the cooled sides of the flask. Stirring is continued for another 15 min. The mixture is poured into 1 N aqueous hydrochloric acid, the phases are separated, and the aqueous phase is washed with 25 mL of methylene chloride. The combined organic phases are washed successively with aqueous sodium bicarbonate and brine, dried over anhydrous sodium sulfate, and filtered. The filtrate is concentrated under reduced pressure and the residue is subjected to flash chromatography4 on 150 g of silica gel (hexane-ethyl acetate 2:1, v/v) to give 10.1 g (89%) of the cycloadduct as colorless crystals, mp 68–69°C.


    Prev:No record
    Next:No record
  • Back】【Close 】【Print】【Add to favorite
Periodic Table
    Hot Products