反应详情

A solution of 4-methyl-5-(2-methyl-propenyl)-thiophene-2-carboxylic acid methyl ester (4.08 g, 19.4 mmol) in methanol (33 mL) is treated with 2 N aq. LiOH solution (10 mL). The mixture is stirred at rt for 2 h, then at 45° C. for 3 h. The reaction mixture is diluted with diethyl ether. The org. layer is separated and extracted with water. The combined aq. phase is acidified with 1 M aq. HCl, and extracted twice with diethyl ether. The combined second org. extracts are dried over MgSO4, filtered and concentrated to give 4-methyl-5-(2-methyl-propenyl)-thiophene-2-carboxylic acid (3.05 g) as an off-white solid; LC-MS: tR=0.92 min, [M+1]+=196.98.

1. waitat 45° C. for 3 h
2. customlayer is separated
3. extractionextracted with water
4. extractionextracted twice with diethyl ether
5. dry with materialextracts are dried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated