Reaktion #465992

Reaktionsgleichung

6-bromo-5,8-dimethyl-4-thiochromanone

ethanediol

p-toluenesulfonic acid monohydrate

→

6-Bromo-5,8-dimethylspiro[thiochromane-4,2′-[1,3]dioxolane]

Lösungsmittel

trimethyl orthoformate

diethyl ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturto cool
2. 2
   Waschenwashed with a 1:1 mixture of 1 M aqueous sodium hydroxide solution and sat. NaCl solution (2×500 ml) and subsequently with sat. NaCl solution (300 ml)
3. 3
   TrocknenThe organic phase was dried over MgSO4
4. 4
   Einengenconcentrated
5. 5
   Sonstigea rotary evaporator
6. 6
   SonstigeThe crystals which had precipitated overnight
7. 7
   Filtrationwere filtered off with suction
8. 8
   Waschenwashed with cold heptane
9. 9
   Sonstigedried

Vorschrift

58.4 g (0.22 mol) of 6-bromo-5,8-dimethyl-4-thiochromanone were dissolved in 380 ml of trimethyl orthoformate, admixed with 555 g (8.9 mol) of ethanediol and 0.2 g of p-toluenesulfonic acid monohydrate and stirred at 80° C. overnight. The mixture was subsequently allowed to cool, diluted with 500 ml of diethyl ether and washed with a 1:1 mixture of 1 M aqueous sodium hydroxide solution and sat. NaCl solution (2×500 ml) and subsequently with sat. NaCl solution (300 ml). The organic phase was dried over MgSO4 and concentrated using a rotary evaporator. The residue was taken up in 50 ml of heptaneldiethyl ether (9:1) and stored in a cold place. The crystals which had precipitated overnight were filtered off with suction, washed with cold heptane and dried.

Quelle