Reaktion #62614

Reaktionsgleichung

4-[(trimethylsilyl)oxy]-2H-1-benzopyran

ether

isopropyl ether

→

orange-red solid

Ausbeute 86.0%

4H-Furo[3,2-c][1]benzopyran-2,3-dione

Ausbeute 86.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   FiltrationThe precipitate is collected by filtration
2. 2
   Waschenwashed with isopropyl ether

Vorschrift

To a stirred solution of 4-[(trimethylsilyl)oxy]-2H-1-benzopyran (L. H. Hellberg, and A. Zuarez, Tetrahedron Letters, 40, 3553 (1974)) (205.8 g, 0.917 mole) in anhydrous ether (600 ml) oxalyl chloride (58.2 g, 0.458 mole) is added dropwise over a period of 40 minutes at room temperature under nitrogen. The suspension is stirred at room temperature for 18 hours and then diluted with isopropyl ether (~300 ml). The precipitate is collected by filtration and washed with isopropyl ether to give 80.2 g (86%) of orange-red solid, mp 146°-8° C. Recrystallization from tetrahydrofuranisopropyl ether gives an analytical sample, mp 146°-148° C.

Quelle