1,8-Diazabicyclo(5.4.0)undec-7-ene → (S)-5-tert-butyl-oxazole-2-carboxylic acid (1-thiophen-2-yl-ethyl)-amide

A solution of carbonyl diimidazole (CDI) (2.42 g, 15 mmol) in THF (40 ml) is added to a stirred solution of 5-tert-butyl-oxazole-2-carboxylic acid (2.3 g, 13.6 mmol) in THF (40 ml). The mixture is stirred for 30 min, then (S)-(1-thiophen-2-yl-ethyl)-amine (2.59 g, 20.4 mmol) is added, followed 10 min later by a solution of DBU (2.24 ml, 15 mmol) in THF (20 ml). The mixture is refluxed for 16 h and the THF is then removed by distillation. The residue is dissolved in ethyl acetate and the organic solution is washed with 2N hydrochloric acid and then twice with water. The organic phase is dried over sodium sulfate and evaporated in vacuo. The residue is purified by flash column chromatography (silica gel, petroleum ether/ethyl acetate 7:3 v/v) to give (S)-5-tert-butyl-oxazole-2-carboxylic acid (1-thiophen-2-yl-ethyl)-amide (2.40 g, 63%) as an oil.

1. temperatureThe mixture is refluxed for 16 h
2. customthe THF is then removed by distillation
3. dissolutionThe residue is dissolved in ethyl acetate
4. washthe organic solution is washed with 2N hydrochloric acid
5. dry with materialThe organic phase is dried over sodium sulfate
6. customevaporated in vacuo
7. customThe residue is purified by flash column chromatography (silica gel, petroleum ether/ethyl acetate 7:3 v/v)

ORD record

ord-28d3a24fc3514b0c880225d10fdbe871

Source dataset

uspto-grants-2000_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06096688