Toluene → Benzopyran

Participants

Reaction Steps

In 100 ml of toluene was dissolved 10 g (0.0328 mole) of a compound represented by the following formula: ##STR256## and 18.71 g (0.00820 mole) of titanium tetraethoxide was added to the solution at room temperature. Ethanol was removed by azeotropic distillation. Then, toluene was added to the residue to form 500 ml of a reaction liquid. Then, a solution of 4.14 g (0.0492 mole) of 3-methyl-2-butenal in 300 m of toluene was added to the reaction liquid and the mixture was refluxed for 8 hours. After the reaction, a saturated aqueous solution of ammonium chloride was added to the reaction liquid and the mixture was extracted with ether. The solvent was removed under reduced pressure and the remaining product was purified by the chromatography on silica gel to obtain 6 g of a chromene compound represented by the following formula: ##STR257##

Provenance & Evidence