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Diels–Alder Reactions of Inert Aromatic Compounds within a Self‐Assembled Coordination Cage
Author(s) -
Horiuchi Shinnosuke,
Murase Takashi,
Fujita Makoto
Publication year - 2011
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201000842
Subject(s) - chemistry , anthracene , diels–alder reaction , adduct , naphthalene , perylene , photochemistry , triphenylene , benzene , substitution reaction , supramolecular chemistry , stereochemistry , medicinal chemistry , organic chemistry , crystal structure , molecule , catalysis
A self‐assembled coordination cage serves as a nanometer‐sized molecular flask to promote the Diels–Alder reactions of aromatic hydrocarbons with N ‐cyclohexylmaleimide. The coordination cage accelerated the Diels–Alder reaction of anthracene at the electronically unfavorable, terminal benzene ring to give a compact, cavity‐restrained syn ‐adduct. Activation‐parameter measurements for the reactions revealed considerable reduction in the entropy cost, and preorganization of the substrates is a dominant factor in the enhanced reactivity. Owing to this entropy‐cost reduction , otherwise‐unreactive aromatic compounds, such as naphthalenes or triphenylene, also underwent Diels–Alder reactions in a regio‐ and stereocontrolled fashion. In the naphthalene Diels–Alder reaction, X‐ray crystallographic analysis of the guest‐inclusion complex clarified the reinforced orientation and proximity of the substrate pairs before the reaction. A perylene Diels–Alder adduct was stabilized inside the cage and protected from aerial oxidation .