New Methods For Cyclopentannulation
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Date
2007Author
Douelle, Frédèric
Metadata
Abstract
A non-exhaustive introduction to well-established synthetic approaches toward
cyclopentannulation is illustrated, which relies on modern aspect reported in between
2003 to present year. Next, our investigations on the validity of novel stereoselective
cyclopentannulation are outlined.
Preliminary studies on nucleophilic catalysis toward the synthesis of cyclopentenone
conducted us to the discovery of a new reagent-free protocol for Nazarov cyclization
that produces highly substituted cyclopentenones in good to excellent yields. These
neutral reaction conditions may enable the extension of Nazarov methodology to acidsensitive
substrates that have been previously inaccessible.
We have also developed the intramolecular iodo-aldol cyclization of enoate aldehydes
and ketones to afford quaternary centre containing hetero and carbocycles. The reaction
transforms simple, pro-chiral starting materials into cyclic alcohols, containing vicinal
quaternary and secondary/tertiary stereocentres, in good yields with excellent
stereoselectivity. In addition, the products display a collection of orthogonal functional
groups that may be further elaborated in the synthesis of complex natural product
targets.
Finally, we have produced 5-monosubstituted tetronic acid derivatives through a simple
and selective Pd-π-allyl-mediated cyclization. Although catalytic and asymmetric
aspects of the reaction remain to be investigated, these preliminary may be incorporated
into a racemic synthesis of the natural product vertinolide.