反应详情

A suspension of potassium tert-butylate (336 mg) in toluene (2.5 ml) is refluxed for 10 min. Then 5-(benzyl-ethoxycarbonylmethyl-amino)-pentanoic acid (695 mg) in toluene (1 ml) is slowly added to the suspension and when the addition is complete the mixture is refluxed for another 1.5 hours. After cooling to room temperature 25% hydrochloric acid (1 ml) is added. The organic phase is separated off and washed with 25% hydrochloric acid (4×1 ml). The combined hydrochloric-acid aqueous phases are then refluxed for 5 hours. After cooling to room temperature the solution is made alkaline (pH 11) with 2N caustic soda solution and extraction is carried out with ethyl acetate. The combined organic phases are concentrated by evaporation after drying over sodium sulphate. The obtained residue produces, after chromatography using silica gel (ethyl acetate/heptane 1:5) the desired title compound (197 mg) in a yield of 45% (Bull. Chem. Soc. Jpn. 1956, 29, 631-632; DE2206385).

1. temperatureis refluxed for 10 min
2. additionthe addition
3. temperatureis refluxed for another 1.5 hours
4. additionis added
5. customThe organic phase is separated off
6. washwashed with 25% hydrochloric acid (4×1 ml)
7. temperatureThe combined hydrochloric-acid aqueous phases are then refluxed for 5 hours
8. extractionwith 2N caustic soda solution and extraction
9. concentrationThe combined organic phases are concentrated by evaporation
10. dry with materialafter drying over sodium sulphate
11. customThe obtained residue produces