Pentane → Chroman

Participants

Reaction Steps

5.1 gm of 3-methyl-1-bromo-2-butene was combined with 4 gm of 3,4-methylenedioxyphenol and dissolved in 50 ml. of pentane and 50 ml. benzene. 2 gm of anhydrous ZnCl2 was added and the reaction mixture refluxed for 1 hour and cooled. The mixture was extracted with ether and washed successively with 100 ml. of water, 100 ml. 5% sodium carbonate and 100 ml. of saturated salt solution. After drying the extract over anhydrous sodium sulfate, the solvent was removed in vacuo leaving 7.4 g of crude chromane. The crude material was fractionated on a column of Florisil and eluted with increasing concentrations of ether in petroleum ether to yield 4.5 g of pure chromane.

Provenance & Evidence