反应详情

温度

0 °C

Crude (R)-5-Biphenyl-4-ylmethyl-3-[1-dimethylaminometh-(E/Z)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (7-a, R1=Boc, R6=Me, R7=Me) (67.5 g) is dissolved in THF (340 ml) and cooled to 0° C. Hydrochloric acid (37%; 13.1 ml) is added followed by water (143.4 ml). Mixture is stirred at room temperature for 2 h. Phases are separated. To the organic phase is added formaldehyde solution (37% in water; 138 ml). Potassium carbonate (31.8 g) is added portionwise over 4 h. 1% Tetra-n-butylammoniumhydroxide solution (14.2 ml) is added followed by sodium hydroxide solution (30% in water) until pH 10.5. The mixture is stirred for 2 h. The phases are separated. The organic phase is washed with water (100 ml) and sodium bisulfite (20 g) added. Toluene (100 ml) and sodium chloride solution (20%; 50 ml). The phases are separated. The organic phase is extracted with a sodium chloride solution (20%; 50 ml), dried (Na2SO4) and concentrated in vacuo to give (R)-5-biphenyl-4-ylmethyl-3-methylene-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (4-a, R1=Boc) (63 g). The material can be recrystallised as follows: crude (R)-5-biphenyl-4-ylmethyl-3-methylene-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (4-a, R1=Boc) (58.4 g) is dissolved in methanol (525 ml) at 50° C. Water (175 ml) is added and the mixture is cooled to 0° C. The solid is collected by filtration and the cake washed with a mixture of methanol (53 ml) and water (18 ml). The solid is then dried in vacuo, giving (R)-5-biphenyl-4-ylmethyl-3-methylene-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (4-a, R1=Boc). Spectroscopic data as Example 23.

1. customPhases are separated
2. additionTo the organic phase is added formaldehyde solution (37% in water; 138 ml)
3. additionPotassium carbonate (31.8 g) is added portionwise over 4 h
4. addition1% Tetra-n-butylammoniumhydroxide solution (14.2 ml) is added
5. stirringThe mixture is stirred for 2 h
6. customThe phases are separated
7. washThe organic phase is washed with water (100 ml) and sodium bisulfite (20 g)
8. additionadded
9. customThe phases are separated
10. extractionThe organic phase is extracted with a sodium chloride solution (20%; 50 ml)
11. dry with materialdried (Na2SO4)
12. concentrationconcentrated in vacuo