Recent Advances in Asymmetric Diels-Alder Reactions (pp. 179-220)
Authors: (Jonathan P. Miller, Oxford International College of Chengdu, Chenghua District, Chengdu, P. R. China)
Abstract: Since the discovery of the Diels-Alder reaction over eighty years ago, it has
transformed a synthetic chemist's arsenal of tools to construct intermolecular and
intramolecular cyclic rings. More importantly, these pericyclic reactions are being
utilised for their stereocontrol to provide chiral building blocks and target compounds,
including those with heteroatoms, with high enantioselectivities. Its versatility can
provide up to four contiguous asymmetric centres with good yields, as many as three
carbocyclic rings in the intramolecular and transannular variations, endo-selectivity and
facile manipulation of the cycloadducts. Many chiral auxiliaries are being used either on
the diene or dienophile, such as D-glucose. Historically, there was a preference for chiral
transition-metal complexes/Lewis acids or enzymes and more recently organocatalysts
(including secondary amines) are gaining prominence with achiral substrates as well as
new transition metal catalysts for even better stereocontrol. Hetero-Diels-Alder reactions
(e.g. the aza-Diels-Alder) are also widely reported in asymmetric synthesis and special
attention will be paid to these, including those with inverse-electron-demand.
This review sources the more recent advances presented in the chemical literature
with a view to constructing biologically interesting and diverse molecules of interest to
the pharmaceutical and related industries. Some classics (in part) are also described. The
review focuses on the mechanism of the Diels-Alder and related reactions where
required, endo-transition states, regioselectivities and HOMO-LUMO orbital interactions.
This builds upon earlier reviews and book chapters and pulls together important
developments in the areas highlighted above concisely into a single chapter.
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