Reacción #1669592

Ecuación de reacción

3,4-dihydroxythiophene-2,5-dicarboxylic acid diethyl ester

ethylene glycol

→

2,3-dihydro-thieno[3,4-b][1,4]dioxine-5,7-dicarboxylic acid diethyl ester

Rendimiento 95.3%

Disolventes

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturarefluxed for 9 h
2. 2
   Concentraciónconcentrated by rotary evaporator
3. 3
   Otroto remove the THF
4. 4
   workup.ADDITIONThe residue was diluted with diethyl ether
5. 5
   workup.WAITto stand overnight
6. 6
   Otroto precipitate out
7. 7
   OtroThe tributylphosphine oxide was then removed by filtration
8. 8
   Otrothe residue purified by chromatography on silica gel (eluant: ethyl acetate/ hexane=2/1)

Procedimiento

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.

Fuente