ethyl 2-[(2-methylpropan-2-yl)oxycarbonylamino]acetate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethyl 2-(tert-butoxycarbonylamino)acetate (4.17 g, 20.52 mmol) was dissolved in tetrahydrofuran (60 ml). The solution was cooled to -78° C. A 22% solution of methyl magensium chloride in toluene/tetrahydrofuran (purchased from Chemmetallgesellschaft, 27.1 ml, 67.72 mmol) was added dropwise. The reaction mixture was stirred for 1.5 h at -78° C. and then warmed to room temperature. A 10% aqueous solution of ammonium chloride (200 ml) was added dropwise. The phases were separated. The aqueous phase was extracted with ethyl acetate (3×100 ml). The combined organic layers were washed with saturated sodium hydrogen carbonate solution (200 ml) and dried over magnesium sulfate. The solvent was removed in vacuo. The crude product was purified by flash chromatography on silica (110 g), using ethyl acetate/heptane (1:1) as eluent, to give 1.31 g of 2-hydroxy-2-methylpropylcarbamic acid tert-butyl ester. warmed to room temperature The phases were separated The aqueous phase was extracted with ethyl acetate (3×100 ml) The combined organic layers were washed with saturated sodium hydrogen carbonate solution (200 ml) dried over magnesium sulfate The solvent was removed in vacuo The crude product was purified by flash chromatography on silica (110 g)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (tert-Butoxycarbonylamino)acetic acid (4.00 g, 22.8 mmol) was dissolved in dichloromethane (8 ml). Ethanol (1.60 ml, 27.40 mmol) and 4-dimethylaminopyridine (0.31 g, 25.1 mmol) were added. The solution was cooled to 0° C. N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (4.81 g, 25.11 mmol) was added. The solution was stirred for 16 h, while warming up to room temperature. It was diluted with ethyl acetate (150 ml) and 10% aqueous sodium hydrogen sulfate solution (100 ml). The phases were separated. The aqueous phase was extracted with ethyl acetate (4×50 ml). The combined organic layers were washed with saturated sodium hydrogen carbonate solution (150 ml) and dried over magnesium sulfate. The solvent was removed in vacuo. The crude product was purified by flash chromatography on silica (100 g), using ethyl acetate/heptane (1:4) as eluent, to give 4.25 g of ethyl 2-(tert-butoxycarbonylamino)acetate. while warming up to room temperature The phases were separated The aqueous phase was extracted with ethyl acetate (4×50 ml) The combined organic layers were washed with saturated sodium hydrogen carbonate solution (150 ml) dried over magnesium sulfate The solvent was removed in vacuo The crude product was purified by flash chromatography on silica (100 g)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a refluxing suspension of 1.58 g (66 mmol) sodium hydride in 100 ml THF was added dropwise a solution of 12.79 g (60 mmol) N-tert-butyloxycarbonyl-glycine ethyl ester and 7.15 g (66 mmol) ethyl acrylate in 100 ml THF. After the addition was complete the mixture was heated to reflux for additional 2 h. The clear solution was cooled to room temperature, poured on 100 ml ether/100 ml water and acidified under vigorous stirring with 1N hydrochloric acid against methyl orange. The layers were separated and the aqueous layer was extracted three times with ether. The combined organic layers were washed with sat. sodium bicarbonate and brine, dried over MgSO4 and evaporated. Short-path distillation of the residue gave 10.92 g (71%) 4-oxo-pyrrolidine-1,3-dicarboxylic acid 1-tert. butylester 3-ethylester as a colorless oil, b.p. 119°-122° C. (0.2 mbar), which solidified on prolonged standing in the freezer. After the addition was heated to reflux for additional 2 h The layers were separated the aqueous layer was extracted three times with ether The combined organic layers were washed with sat. sodium bicarbonate and brine dried over MgSO4 evaporated Short-path distillation of the residue

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir: