反应详情

At −70° C. a solution of 4-p-tolyl-thiophene-2-carboxylic acid (580 mg, 2.66 mmol) in THF (8 mL) is treated with tert.-BuLi (5 mL, 1.7 M solution in pentane). The mixture is stirred at −70° C. for 30 min before ethyliodide (1.2 mL) is added. The mixture is warmed to rt and stirring is continued for 72 h. The reaction is quenched by adding sat. aq. NH4Cl and the mixture is extracted with DCM. The solvent of the organic extracts is evaporated and the remaining oil (780 mg) is dissolved in dry DCM (10 mL). TBTU (1.42 g, 4.43 mmol), N,O-dimethylhydroxylamine (463 mg, 4.75 mmol) and DIPEA (2 mL) is added and the mixture is stirred at rt for 18 h before it is diluted with EA and washed with water. The organic layer is separated, evaporated and the remaining residue is purified by CC on silica gel eluting with heptane:EA 4:1 to give 5-ethyl-4-p-tolyl-thiophene-2-carboxylic acid methoxy-methyl-amide (210 mg) as an oil. This oil is dissolved in THF and treated at 3° C. with methyl magnesiumbromide (0.3 mL, 3 M solution in THF). The reaction mixture is stirred at rt for 16 h before another portion of the Grignard reagent (0.5 mL) is added. Stirring is continued for 72 h. The mixture is diluted with water and extracted with EA. The solvent of the organic extract is evaporated and the crude product is purified on prep. TLC plates with heptane:EA to give 1-(5-ethyl-4-p-tolyl-thiophen-2-yl)-ethanone (28 mg) as a yellow oil; LC-MS: tR=1.06 min, [M+1]+=245.19.

1. additionis added
2. customThe reaction is quenched
3. additionby adding sat. aq. NH4Cl
4. extractionthe mixture is extracted with DCM
5. customThe solvent of the organic extracts is evaporated
6. dissolutionthe remaining oil (780 mg) is dissolved in dry DCM (10 mL)
7. stirringthe mixture is stirred at rt for 18 h before it
8. washwashed with water
9. customThe organic layer is separated
10. customevaporated
11. customthe remaining residue is purified by CC on silica gel eluting with heptane:EA 4:1