Synthetic Studies on Aromadendrane-Type Compounds. I. Stereoselective Construction of Aromadendrane- and Alloaromadendrane-Type Skeletons

As a preliminary study for the synthesis of aromadendrane- and alloaromadendrane-type compounds, trans and cis B/C-ring compounds (18 and 22) were synthesized from (+)-(1S, 2R, 4R, 7R)-3, 3, 7-trimethyltricyclo[6.3.0.02, 4]undec-8-en-10-one (3) as a common intermediate, which was obtained from (+)-3-carene via an intramolecular aldol condensation as a crucial step.