A laboratory model for the atisane ? aconane conversion

Biogenetic-Type Rearrangements of Terpenes

“…PELLETIER and ICHIHARA first reported that 15-hydroxy-17-noratisane derivatives undergo rearrangement ofthe ethanobridge (C13-Ct4), instead of the C9 -Cs bond (as in 292), regard1ess of the configuration of the hydroxyl group (366). Simi1arly JOHNSTON and ÜVERTON found that buffered acetolysis of either the atisine-derived keto tosylate (290) or its C15 epimer affords only the bridge-rearranged keto olefin (292) (367). However, gas phase pyrolysis of (290) at 600° brings about migration of the C9-C8 bond, providing the seco-aconane derivative (291) in 77% yie1d (367).…”

“…Simi1arly JOHNSTON and ÜVERTON found that buffered acetolysis of either the atisine-derived keto tosylate (290) or its C15 epimer affords only the bridge-rearranged keto olefin (292) (367). However, gas phase pyrolysis of (290) at 600° brings about migration of the C9-C8 bond, providing the seco-aconane derivative (291) in 77% yie1d (367). A cyclic transition state, in which the C14,ß-proton is transferred to the departing sulfonate group, was proposed for this pyrolytic elimination.…”

“…Since the initial suggestion that the aconane skeleton is biogenetically derived from an atisane precursor (363)(364)(365), there have been a number of attempts to effect the proposed Cg-+Cts rearrangement (366)(367)(368). PELLETIER and ICHIHARA first reported that 15-hydroxy-17-noratisane derivatives undergo rearrangement ofthe ethanobridge (C13-Ct4), instead of the C9 -Cs bond (as in 292), regard1ess of the configuration of the hydroxyl group (366).…”

Alkaloids

“…The conversion of the atisane skeleton to the aconitine (402) skeleton was achieved [372] along the commonly accepted biogenetic route for aconitine-type alkaloids. Veatchine (397) and garryine (399) have a kaurene skeleton, and they are the positional isomers of an aminoethanol unit.…”

A Stereoselective Total Synthesis of (±)‐Maritimol, (±)‐2‐Deoxystemodinone, (±)‐Stemodinone, and (±)‐Stemodin

“…We have therefore prepared, from podocarpic acid, the ketones 6 and 7 [lo], models for the ketones 4 and 5, showing that the two systems can be easily synthesized by this approach. R' 5 4a R = R = C H 3 4b R=t-Bu, R'=H 6 7 R = H 26 R=OH 2,Pyrolytic conditions are also possible and were used first for this type of rearrangement [7].…”