Ethylene Glycol → 2-Methyl-2-(thiophen-3-yl)-1,3-dioxolane

A mixture of 3-acetylthiophene (20 g), ethyleneglycol (10.54 g), p-toluenesulfonic acid (0.15 g) and toluene (200 ml) was stirred for 16 hours under reflux with removing azeotropic water by Dean-Stark trap. The mixture was cooled, washed with water, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give 2-methyl-2-(3-thienyl)-1,3-dioxolan (12.6 g). 2-Methyl-2-(3-methyl-2-(3-thienyl)-1,3-dioxolan (12.0 g) was dissolved in tetrahydrofuran (200 ml), and N,N,N',N'-tetramethylethylenediamine (1.3 ml) was added. The mixture was cooled to -78° C, and n-butyllithium (1.6M in hexane, 49 ml) was slowly added dropwise. The mixture was stirred at the same temperature for 2 hours, and then warmed slowly to room temperature for a period of 2 hours with introducing carbon dioxide gas. The reaction mixture was concentrated under reduced pressure, and 2N hydrochloric acid (200 ml) was added. The mixture was stirred for 3 hours, and precipitated crystals were collected by filtration, washed with water and dried to give 3-acetyl-2-thiophenecarboxylic acid (10 g) as crystals.

1. temperatureunder reflux
2. customwith removing azeotropic water by Dean-Stark trap
3. temperatureThe mixture was cooled
4. washwashed with water
5. dry with materialdried over anhydrous magnesium sulfate
6. concentrationconcentrated under reduced pressure
7. customThe residue was purified by silica gel column chromatography

ORD record

ord-5e30c51379d14ac3b0535d31d4d0ec2d

Source dataset

uspto-grants-1998_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05840917