The anionic oxy-Cope rearrangement is widely utilized
as a versatile class of bond reorganization in synthesis.'
In the context of acyclic stereocontrol, however, the acyclic
oxy-Cope methodology still occupies a much lower position
than that of its Claisen counterpart? although several
oxy-Cope rearrangements of rigid, cyclic substrates have
been reported to provide high levels of stereo~ontrol.'~~
The key stereochemical issue inherent in the acyclic oxy-
Cope process is associated with the oxyanion orientation
(axial vs equatorial) in the chairlike transition states.
Related studies4 have shown that the oxyanion stereochemistry
in acyclic systems cannot be effectively controlled
unless other steric demand(s) such as favorable
Ir-facial selectivity is imposed on the pericyclic array. We
now disclose that the acyclic oxy-Cope rearrangement,
when the proper substrate stereochemistry is generated
by the [2,3]Wittig rearrangement: provides a synthetically
useful level of diastereoselection and asymmetric transmission
(Scheme I).
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