Synthetic studies in the diterpene series. Part IX. Synthesis of 1,2,3,4-tetrahydro-1,1,5,7-tetramethyl-6-(3-methylpentyl)naphthalene (Ruzicka's hydrocarbon)

Abstract

1,2,3,4-Tetrahydro-1,1,5,7-tetramethyl-6-(3-methylpentyl)naphthalene (III) has been synthesised from 1,2,3,4-tetrahydro-1,1,5,7-tetramethylnaphthalene (IV) by Friedel–Crafts acylation with 3-methylpentanoyl chloride followed by reduction, and its identity with Ruzicka's hydrocarbon (acid-catalysed dehydration product of sclareol) has been confirmed by i.r. and n.m.r. spectroscopy. An independent synthesis of the derived α-ketone (VI) from a substituted Hagemann's ester is also reported.