Diterpene Synthesis. III. Acid-Catalyzed Cyclization of Methoxyphenylethyltrimethyl-Cyclohexanols, Cyclohexenols and Cyclohexenones

Cyclization of the methoxyphenylethyltrimethylcyclohexanols (3), (4) and (5), the cyclohexenols (6) and (7) and the cyclohexenones (20) and (21), in the presence of a variety of acids, has been studied and the products analysed by chromatographic and spectroscopic techniques. Both cis - and trans-podocarpa-8,11,13-trienes are formed, along with the rearranged compounds (16), (17) and (30). These results parallel our earlier findings and contrast with some reports in the literature.