CONVENIENT SYNTHESES OF 5,5,9-TRIMETHYL-TRANS-1-DECALONE AND 6-BETA-HYDROXY-5,5,9-BETA-TRIMETHYL-TRANS-1-DECALONE

Convenient syntheses of 5, 5, 9-trimethyl-trarcs-1-decalone (1) and 6β-hydroxy-5, 5, 9β-trimethyl-frans-1-decalone (2) involve (1) the Robinson annelation of 2-methyl-1, 3-cyclohexanedione with ethyl vinyl ketone, (2) selective ketalization of 5, 9-dimethyl-Δ5, 10-octal-1, 6-dione at the nonconjugated carbonyl group with ethylene glycol, (3) reductive methylation of 1-ethylenedioxy-5, 9-dimethyl-Δ5, 10-2-octalone, (4) Wolff-Kishner reduction or dissolving-metal reduction of 1-ethylenedioxy-5, 5, 9-trimethyl-trans-1-decalone, and (5) acid-catalyzed hydrolysis of 1-ethylenedioxy-5, 5, 9-trimethyl-trans, 9β-trimethyl-trans-decalin to form 1 and 2, respectively. © 1979, American Chemical Society. All rights reserved.