We have accomplished highly enantioselective [2,3]-Wittig rearrangements of functionalized allyl benzyl ethers in the presence of a chiral di-tBu-bis(oxazoline) ligand. In various oxygenated benzylic ethers, the reactions proceeded with excellent diastereo- and enantioselectivities, although the presence of a methoxy substituent at the ortho-position on the benzyl group drastically decreased the enantioselectivity. Conversely, o-ethyl and o-phenyl substituents had no significant effect on the selectivity. We found that the C2-substituent of the allylic moiety played an important role in producing high enantioselectivity. Highly enantioselective [2,3]-Wittig rearrangement in the presence of catalytic amounts of the chiral ligands is also described.

In this study, the asymmetric total synthesis of eupomatilones 1, 2, and 5 has been accomplished. These compounds are lignan congeners containing a biaryl system bearing an α‐methylene γ‐lactone. They were isolated from the Australian shrub Eupomatia bennettii. Two chiral centers were constructed enantioselectively by the asymmetric [2,3]‐Wittig rearrangement of highly oxygenated biaryl compounds, using a bis(oxazoline) chiral ligand. Optimization of the key reaction using nBuLi as the base and ether as the co‐solvent increased the enantioselectivity to 88–91 % ee.

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