Diethyl Ether → Ethyl 3-oxo-3-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-propionate

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Reaction Steps

15 g (0.23 mole) of zinc powder and 1.5 g (8.3 millimoles) of copper(II) acetate monohydrate in 50 ml of glacial acetic acid were stirred for 30 minutes while cooling with ice. The mixture was then stirred with 50 ml of dry ether, and the solid was filtered off under suction and washed twice with dry ether and once with dry tetrahydrofuran. The solution of 21.6 g (0.1 mole) of 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthaldehyde and 21.0 g (0.125 mole) of ethyl bromoacetate in 500 ml of dry tetrahydrofuran was added dropwise to a suspension of a zinc/copper product pair prepared in this manner, the reaction reaching the reflux -temperature. The refluxing mixture was stirred for a further 75 minutes, cooled, acidified with 5 N sulfuric acid and filtered. The filtrate was extracted with ether and the organic phase was washed with water, dried over sodium sulfate and evaporated down. The residue (27.8 g) was dissolved in 100 ml of acetone, and a solution of 12.0 g (0.12 mole) of chromium(VI) oxide in 36.8 ml of water and 12.9 ml of concentrated sulfuric acid was added dropwise at 10° C. Stirring was continued for 30 minutes at 10° C., after which the mixture was poured onto ice/water and was extracted with ether. The organic phase was washed twice with water, dried over sodium sulfate and evaporated down. Distillation of the residue gave 9.0 g of ethyl 3-oxo-3-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-propionate of boiling point 150°-152° C./0.4 mbar.

Provenance & Evidence