title: Conformationally flexible chiral supramolecular catalysts for enantioselective Diels-Alder reactions with anomalous endo/exo selectivities.
abstract: The potential of supramolecular catalysts to realize anomalous regio- and/or stereoselectivity in organic synthesis is highly attractive. To date, there have been a few examples of non-polymeric and non-covalent chiral supramolecular catalysts that induce practical enantioselectivity. In this regard, a metal-organic framework (MOF) may be one of the most important techniques for constructing conformationally rigid supramolecular catalysts. However, it is not easy to use the MOF technique to fine-tune a much more precise cage in catalysts for anomalous purposes. To establish high catalytic activity with anomalous regio- and/or stereoselectivity, in principle, an artificial cage should be conformationally flexible, like an active pocket in an enzyme with an induced-fit function. In this feature article, we focus on the anomalous endo/exo-selective Diels-Alder reaction, and overview the development of the successive catalysts including our recent highly active, conformationally flexible, and chiral supramolecular catalysts. The evolution from 'ready-made' single-molecule catalysts to 'tailor-made' supramolecular catalysts could offer not only high enantioselectivity but also high anomalous endo/exo-selectivities due to substrate-specific characteristics, as with enzymes.
authors.affiliation: Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Hatano
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ishihara