反応 #1669592

反応方程式

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

収率 95.3%

溶媒

tetrahydrofuran

反応条件

後処理

1. 1
   温度refluxed for 9 h
2. 2
   濃縮concentrated by rotary evaporator
3. 3
   その他to remove the THF
4. 4
   workup.ADDITIONThe residue was diluted with diethyl ether
5. 5
   workup.WAITto stand overnight
6. 6
   その他to precipitate out
7. 7
   その他The tributylphosphine oxide was then removed by filtration
8. 8
   その他the residue purified by chromatography on silica gel (eluant: ethyl acetate/ hexane=2/1)

実験手順

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.

出典