1,2,3-Trimethylindene → HCID 13280229, compound

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Reaction Steps

In a 1 liter three necked round bottomed flask fitted with a magnetic stirring apparatus and a reflux condenser 2,3-dimethyl-1-indanone (34) (19.2 g, 0.12 mol) was dissolved in dry diethyl ether (300 ml) under an argon atmosphere. Methyllithium (46.3 ml, 3 M solution in diethoxymethane, 0.14 mol) was added dropwise via a syringe and the mixture was refluxed overnight. The mixture was cooled to 0° C. and a solution of saturated ammonium chloride (100 ml) was added dropwise through the top of the condenser. The mixture was transferred into a separation funnel, the organic layer was washed with water (3×100 ml), dried over magnesium sulfate and filtered. The ether was removed under reduced pressure to afford the raw 1,2,3-trimethyl-1-indanol (19.34 g, 92%) as a yellow liquid which was used for the next step without further purification. Toluene (300 ml) was added to the raw 1,2,3-trimethyl-1-indanol (19.34 g, 0.11 mol) and the solution was transferred into a 500 ml round bottomed flask fitted with a Dean-Stark trap and a magnetic stirring apparatus. p-Toluene sulfonic acid (50 mg, 0.26 mmol) was added and the solution refluxed overnight. After completion of the removal of the water the excess toluene was removed via distillation through the Dean-Stark arm, the residue was cooled to ambient temperature, diluted with diethyl ether (100 ml), washed with a saturated solution of sodium bicarbonate (3×100 ml), dried over magnesium sulfate and filtered. After removal of the solvent in vacuo, the liquid was purified via column-chromatography [(SiO2, 50×9 cm) eluent: cyclohexane:ethylacetate (10:1)] to afford two fractions: 1,2,3-Trimethylindene (37) (8.92 g, 51%) as a pale yellow liquid Rf 0.41; (34) (7.94 g, 45%) (starting material) was obtained as a dark yellow liquid.

Provenance & Evidence