ORGN 425

Montanin B (1) and 12-epi-montanin B (2) are 19-nor-clerodanoids isolated respectively from the bitter fraction of Bulgarian Teucrium montanum L. and the acetone-soluble extracts of the aerial parts of Teucrium maghrebinum. We have recently embarked on a project directed towards the total synthesis of these two furan-containing nor-diterpenoids. Under zinc chloride catalysis, the Diels-Alder addition of 2,4-pentadienol to enone 3, readily prepared from diethyl succinate in five steps, proceeded with complete face-, regio-, and stereoselectivity to give adduct 4. This compound was converted to the advanced intermediate 5 via a sequence of eight synthetic operations. The transformation of this projected synthetic intermediate to the target natural products is under current investigation. Details of the synthetic studies will be described.