A thermally allowed tropone-diene [6u+ 47rI cycloaddition is employed to produce a functionally rich BC ring building block for the construction of 8-isoingenol intermediates. Bridgehead enolate alkylation followed by aldol condensation is used to install the elements of the A-ring. Stereo-and regioselective bis-hydroxylation at C-13 and-14 of the C-ring followed by activation as the correaponding bis-mesyloxy derivative and treatment with ...