Novel Diastereoselective Routes for the Synthesis of the Ambergris ketals

Article abstract of DOI:10.1016/S0040-4039(00)78512-1

New processes have been developed which allow the stereoselective syntheses of the ambergris ketals 8α,13;13,17-diepoxi-14,15-dinorlabdane 1 and 8β,13;13,17-diepoxi-14,15-dinorlabdane 2, through selection of the appropriate catalyst for the δ,ε-epoxycarbonyl rearrangement of the key intermediate 3, which is, in turn, obtained by controlled oxidation of anticopalic acid 6.