Acetyl chloride → 1-(5,5,8,8-Tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)ethan-1-one

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Reaction Steps

5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-naphthalene is reacted with acetyl chloride and aluminium chloride in nitrobenzene to give (5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl) methyl ketone. Reduction of this ketone with lithium aluminium hydride in ether yields 5,6,7,8-tetrahydro-α-5,5,8,8-pentamethyl-2-naphthalene-methanol which is converted by treatment with phosphorus tribromide in ether/hexane in the presence of a small amount of pyridine into 2-bromoethyl-5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-naphthalene. This bromoethyl compound is converted by treatment with triphenylphosphine in xylene while heating for 12 hours into [1-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-ethyl]-triphenylphosphonium bromide which, in a Wittig reaction with 4-ethoxycarbonyl-benzaldehyde, yields p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-propenyl]-benzoic acid ethyl ester of melting point 90°-91° C. This ester is reduced with lithium aluminum hydride in ether/tetrahydrofuran to give p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-propenyl]-benzyl alcohol of melting point 123°-124° C. (from methanol).

Provenance & Evidence