Ethylene Glycol → Diethyl 2,3-dihydrothieno[3,4-b][1,4]dioxine-5,7-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

ADC01 (2.9 g, 16.9 mmol) was slowly added to a solution of 3,4-dihydroxythiophene-2,5-dicarboxylic acid diethyl ester (2.0 g, 7.7 mmol), ethylene glycol (0.5 g, 8.5 mmol), and PHOL (3.4 g, 16.9 mmol) in dry tetrahydrofuran (150 ml) at 25° C. The reaction mixture was stirred for 3 h and then refluxed for 9 h. The reaction mixture was allowed to cool to 25° C. and concentrated by rotary evaporator to remove the THF. The residue was diluted with diethyl ether and allowed to stand overnight to enable the tributylphosphine oxide to precipitate out. The tributylphosphine oxide was then removed by filtration and the residue purified by chromatography on silica gel (eluant: ethyl acetate/ hexane=2/1) to give 2.1 g of 2,3-dihydro-thieno[3,4-b][1,4]dioxine-5,7-dicarboxylic acid diethyl ester as white crystals (95% yield) as fully characterized by 1H NMR, 13C NMR, HRMS, and elemental analysis.

Provenance & Evidence