Mechanistic analysis of the Fraser-Reid -silphiperfolene synthesis

4 Mechanistic analysis of the Fraser-Reid (—)-silphiperfolene synthesis 

Dickson and B. Fraser-Reid, 1990, J. Chem. Soc., Chem. Commun., 141. 

For a detailed discussion of the rules for radical ring-closure, see A.L.J. Beckwith, C.J. Easton and A.K. Serelis, 1980, J. Chem. Soc., Chem. Commun., 482. For Baldwin s earlier rules for ring-closure, see J.E. Baldwin, 1976, J. Chem. Soc., Chem. Commun., 734. 

Synthetic interest in (—)-alloasamizoline has risen steadily ever since its structure was first announced in the mid-1980s. Trost and Van Vranken2 were the first to report a racemic synthesis, in 1990, and there later followed two enantiospecific syntheses by Kuzuhara et al and Simpkins and Stokes4 in 1991 and 1992, respectively. 

Let us return now to the (—)-allosamizoline question. If Kuzuhara s intention was to derive three of the target s chiral centres from 

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