Diisopropylamine → 1-(4-Benzyloxy-2-tert-butoxycarbonylbutyl)cyclopentane carboxylic acid

Temperature

-40 °C

To a solution of diisopropylamine (2.9 mL, 20.8 mmol) in dry tetrahydrofuran (50 mL) at -50° C. was added a 2.5M solution of n-butyllithium in hexane (8.4 mL, 21 mmol). The mixture was stirred at a temperature from -30° C. to 0° C. over 30 minutes and then cooled again to -40° C. A solution of cyclopentanecarboxylic acid (1.1 mL, 10.1 mmol) in tetrahydrofuran (20 mL) was added and the resulting mixture was allowed to warm to room temperature with stirring over 2 hours. The reaction was cooled to -79° C. and a solution of 2-(2-benzyloxyethyl) acrylic acid tert-butyl ester (2.6 g, 9.9 mmol) in dry tetrahydrofuran (10 mL) was added dropwise; stirring was continued at -40° C. for 2 hours. The mixture was quenched by the addition of 0.5M HCl solution and was extracted with ether. The extract was washed with brine, dried over MgSO4 and evaporated under vacuum to leave an oil from which 1-(4-benzyloxy-2-tert-butoxycarbonylbutyl)cyclopentane carboxylic acid, 2.9 g (78%), was isolated by chromatography on silica gel eluting with methylene chloride and then 1% methanol in methylene chloride.

1. temperatureto warm to room temperature
2. stirringwith stirring over 2 hours
3. temperatureThe reaction was cooled to -79° C.
4. stirringstirring
5. waitwas continued at -40° C. for 2 hours
6. customThe mixture was quenched by the addition of 0.5M HCl solution
7. extractionwas extracted with ether
8. washThe extract was washed with brine
9. dry with materialdried over MgSO4
10. customevaporated under vacuum

ORD record

ord-d322f8958c3e40bebff669be2da5413c

Source dataset

uspto-grants-1998_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05854275