Taxol precursors cycloadditions

Magnus and co-workers (158-162) used the power of the oxidopyrylium cycloaddition to prepare a taxol precursor 288, generating a synthon for the taxol... 

A similar approach was employed en route to a synthesis of taxol precursors, as shown in Scheme 14 <1996T14081>. In this case, a [5+2] cycloaddition reaction of 133 yielded diastereoisomers 134a and 134b. 

The cationic zirconium-mediated aldehyde addition methodology has recently been used by Maier and coworkers in their study toward the taxol skeleton [57] (Scheme 10). The diene precursor to a planned cycloaddition was prepared by first adding zirconocene 40 to aldehyde 41 under silver(I)-catalysis, which afforded alcohol 42 as a 77 23 mixture of diastereomers. Protection of the... 

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