Hydrochloric Acid → Ethanone, 1-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphthalenyl)-

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Reaction Steps

To a 250 ml three-necked round bottomed flask fitted with a magnetic stirring bar and a reflux condenser containing acetyl chloride (2.3 g, 29.7 mmol) and 50 ml of DCM was added 1,1,4,4,6-pentamethyl-1,2,3,4-tetrahydronaphthalene 1b (5 g, 24.8 mmol) followed by slow addition (ca. 0.5 g portions) of AlCl3 (7.5 g, 56.2 mmol). The brown mixture was stirred for 30 min and then heated at reflux for 15 min. Additional AlCl3 (1-2 g) was necessary to effect the completion of the reaction. The cooled reaction mixture was poured into 200 ml of vigorously stirred ice water followed by acidification with 20% aqueous hydrochloric acid 50 ml and addition of 100 ml of ethyl acetate. Stirring was continued until the organic layer was yellow 15 min. The organic layer was extracted with ethyl acetate (2×100 ml), dried over MgSO4, filtered and concentrated in vacuo. Kugelrohr distillation (80-120° C., 3×10−4 torr) gave an analytically pure sample of 1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene-2-yl)ethanone 5.31 g (88%) as a white solid; m.p. 54-56° C.

Provenance & Evidence