tert-butyl 4-nitrobutanoate

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

Procedure: The racemic product is prepared starting from tert.-butyl 4-nitrobutyrate and N-tert.-butoxycarbonylallylamine in analogy to Example 12. After cleavage of the protecting groups, it is taken up in acetone and the betaine is precipitated by adjusting the pH to 6 by means of conc. aq. ammonia. The melting point is 201° C. (with dec.). The racemic product is prepared the betaine is precipitated

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

Procedure: A solution of 18.9 g of 4-nitrobutyric acid t-butyl ester, 8.6 g of methyl acrylate, 0.2 g triethyl amine in 200 ml of toluene is stirred and treated dropwise with 27.4 g of phenyl isocyanate. The mixture is stirred for 72 hours at room temperature and heated at 90° C. for two hours. The mixture is cooled, filtered to remove the diphenyl urea, and concentrated under reduced pressure. The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25) to yield 4,5-dihydro-5-(methoxycarbonyl)-3-isoxazolepropanoic acid t-butyl ester as a colorless oil. NMR (CDCl3) and 5.00 (t, J=9 Hz, 1H), 3.77 (s, 3HO, 3.28 (d, J=9 Hz, 2H), 2.58 (s, 4H), 1.42 (s, 9H). IR (cm-1) 2955, 2910, 1728, 1545, 1437, 1385, 1370, 1340, 12155, 1215. heated at 90° C. for two hours The mixture is cooled filtered to remove the diphenyl urea concentrated under reduced pressure The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25)

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

Procedure: A solution of 18.9 g of 4-nitrobutyric acid t-butyl ester, 8.6 g of methyl acrylate, 0.2 g triethyl amine in 200 ml of toluene is stirred and treated dropwise with 27.4 g of phenyl isocyanate. The mixture is stirred for 72 hours at room temperature and heated at 90° C. for two hours. The mixture is cooled, filtered to remove the diphenyl urea, and concentrated under reduced pressure. The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25) to yield 4,5-dihydro-5-(methoxycarbonyl)-3-isoxazolepropanoic acid t-butyl ester as a colorless oil. NMR (CDCl3) and 5.00 (t, J=9 Hz, 1H), 3.77 (s, 3HO, 3.28 (d, J=9 Hz, 2H), 2.58 (s, 4H), 1.42 (s, 9H). IR (cm-1) 2955, 2910, 1728, 1545, 1437, 1385, 1370, 1340, 12155, 1215. heated at 90° C. for two hours The mixture is cooled filtered to remove the diphenyl urea concentrated under reduced pressure The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25)

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

Procedure: A solution of 18.9 g of 4-nitrobutyric acid t-butyl ester, 8.6 g of methyl acrylate, 0.2 g triethyl amine in 200 ml of toluene is stirred and treated dropwise with 27.4 g of phenyl isocyanate. The mixture is stirred for 72 hours at room temperature and heated at 90° C. for two hours. The mixture is cooled, filtered to remove the diphenyl urea, and concentrated under reduced pressure. The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25) to yield 4,5-dihydro-5-(methoxycarbonyl)-3-isoxazolepropanoic acid t-butyl ester as a colorless oil. NMR (CDCl3) and 5.00 (t, J=9 Hz, 1H), 3.77 (s, 3HO, 3.28 (d, J=9 Hz, 2H), 2.58 (s, 4H), 1.42 (s, 9H). IR (cm-1) 2955, 2910, 1728, 1545, 1437, 1385, 1370, 1340, 12155, 1215. heated at 90° C. for two hours The mixture is cooled filtered to remove the diphenyl urea concentrated under reduced pressure The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25)

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

Procedure: The racemic product is prepared starting from tert.-butyl 4-nitrobutyrate and N-tert.-butoxycarbonylallylamine in analogy to Example 12. After cleavage of the protecting groups, it is taken up in acetone and the betaine is precipitated by adjusting the pH to 6 by means of conc. aq. ammonia. The melting point is 201° C. (with dec.). The racemic product is prepared the betaine is precipitated

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

Procedure: The racemic product is prepared starting from tert.-butyl 4-nitrobutyrate and N-tert.-butoxycarbonylallylamine in analogy to Example 12. After cleavage of the protecting groups, it is taken up in acetone and the betaine is precipitated by adjusting the pH to 6 by means of conc. aq. ammonia. The melting point is 201° C. (with dec.). The racemic product is prepared the betaine is precipitated

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

Procedure: A solution of 18.9 g of 4-nitrobutyric acid t-butyl ester, 8.6 g of methyl acrylate, 0.2 g triethyl amine in 200 ml of toluene is stirred and treated dropwise with 27.4 g of phenyl isocyanate. The mixture is stirred for 72 hours at room temperature and heated at 90° C. for two hours. The mixture is cooled, filtered to remove the diphenyl urea, and concentrated under reduced pressure. The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25) to yield 4,5-dihydro-5-(methoxycarbonyl)-3-isoxazolepropanoic acid t-butyl ester as a colorless oil. NMR (CDCl3) and 5.00 (t, J=9 Hz, 1H), 3.77 (s, 3HO, 3.28 (d, J=9 Hz, 2H), 2.58 (s, 4H), 1.42 (s, 9H). IR (cm-1) 2955, 2910, 1728, 1545, 1437, 1385, 1370, 1340, 12155, 1215. heated at 90° C. for two hours The mixture is cooled filtered to remove the diphenyl urea concentrated under reduced pressure The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25)

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

Procedure: A solution of 18.9 g of 4-nitrobutyric acid t-butyl ester, 8.6 g of methyl acrylate, 0.2 g triethyl amine in 200 ml of toluene is stirred and treated dropwise with 27.4 g of phenyl isocyanate. The mixture is stirred for 72 hours at room temperature and heated at 90° C. for two hours. The mixture is cooled, filtered to remove the diphenyl urea, and concentrated under reduced pressure. The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25) to yield 4,5-dihydro-5-(methoxycarbonyl)-3-isoxazolepropanoic acid t-butyl ester as a colorless oil. NMR (CDCl3) and 5.00 (t, J=9 Hz, 1H), 3.77 (s, 3HO, 3.28 (d, J=9 Hz, 2H), 2.58 (s, 4H), 1.42 (s, 9H). IR (cm-1) 2955, 2910, 1728, 1545, 1437, 1385, 1370, 1340, 12155, 1215. heated at 90° C. for two hours The mixture is cooled filtered to remove the diphenyl urea concentrated under reduced pressure The resulting oil is chromatographed on SiO2 (elution with hexane:ethylacetate; 75:25)

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

Procedure: The racemic product is prepared starting from tert.-butyl 4-nitrobutyrate and N-tert.-butoxycarbonylallylamine in analogy to Example 12. After cleavage of the protecting groups, it is taken up in acetone and the betaine is precipitated by adjusting the pH to 6 by means of conc. aq. ammonia. The melting point is 201° C. (with dec.). The racemic product is prepared the betaine is precipitated