Conversion of acetyl cedrene (2) to its follower (3) using acetic anhydride and polyphosphoric acid involves a multi-step cationic molecular rearrangement, which is consistent with deuteriation and 1-¹³C labeling studies of acetyl cedrene. The key step involves cyclopropylcarbinyl cation-cyclopropylcarbinyl cation rearrangement.

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