Sophora compounds, synthesis

If the precursor dienes have vinyl end-groups, ethene is eliminated in the metathesis reaction, but it is sometimes advantageous to use a precursor with one or two propenyl end-groups, eliminating propene or but-2-ene in the metathesis reaction. An example is shown in equation 31, the final stage in the synthesis of the protected precursor (42) of Sophora compound I, the antifungal phytoalexine isolated from the aerial part of Sophora tomentosa L228. 

The direct method using ene-ene RCM to construct aromatic rings has also been used for the synthesis of benzofurans and indoles. In a paper on the synthesis of cyclic enol ethers by RCM, Fujimura et al. reported that benzofurans 27 could be prepared from dienes 26 by RCM using Schrock s catalyst 4 (Scheme 26.7) [14]. This group applied the method to obtain the naturally occurring antifungal phytoalexine, known as Sophora compound I (30). On the other hand, Arisawa et al. synthesized indoles... 

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